diff --git a/src/emu/kernel/setup.c b/src/emu/kernel/setup.c
index b25c9a5..34187e5 100644
--- a/src/emu/kernel/setup.c
+++ b/src/emu/kernel/setup.c
@@ -20,8 +20,9 @@ static const char model_name[] = "kernel";
 enum { model_id = 'K' };
 
 struct model_spec model_kernel = {
-	.name = model_name,
-	.model = model_id,
+	.name    = model_name,
+	.version = "1.0.0",
+	.model   = model_id,
 	.create  = model_kernel_create,
 //	.connect = model_kernel_connect,
 	.event   = model_kernel_event,
@@ -117,10 +118,7 @@ static const struct model_thread_spec th_spec = {
 int
 model_kernel_probe(struct emu *emu)
 {
-	if (emu->system.nthreads == 0)
-		return 1;
-
-	return 0;
+	return model_version_probe(&model_kernel, emu);
 }
 
 int
diff --git a/src/emu/model.c b/src/emu/model.c
index 8daf7d8..2a4ecdc 100644
--- a/src/emu/model.c
+++ b/src/emu/model.c
@@ -4,7 +4,9 @@
 #include "model.h"
 #include <string.h>
 #include "common.h"
-struct emu;
+#include "version.h"
+#include "emu.h"
+#include "thread.h"
 
 void
 model_init(struct model *model)
@@ -17,6 +19,16 @@ model_register(struct model *model, struct model_spec *spec)
 {
 	int i = spec->model;
 
+	if (spec->name == NULL) {
+		err("model %c missing name", i);
+		return -1;
+	}
+
+	if (spec->version == NULL) {
+		err("model %c missing version", i);
+		return -1;
+	}
+
 	if (model->registered[i]) {
 		err("model %c already registered", i);
 		return -1;
@@ -47,10 +59,10 @@ model_probe(struct model *model, struct emu *emu)
 		}
 
 		if (ret == 0) {
+			dbg("model %c disabled", (char) i);
+		} else {
 			model->enabled[i] = 1;
 			dbg("model %c enabled", (char) i);
-		} else {
-			dbg("model %c disabled", (char) i);
 		}
 	}
 	return 0;
@@ -141,3 +153,58 @@ model_finish(struct model *model, struct emu *emu)
 
 	return ret;
 }
+
+int
+model_version_probe(struct model_spec *spec, struct emu *emu)
+{
+	int enable = 0;
+	int have[3];
+
+	if (version_parse(spec->version, have) != 0) {
+		err("cannot parse version %s", spec->version);
+		return -1;
+	}
+
+	char path[128];
+	if (snprintf(path, 128, "%s.version", spec->name) >= 128)
+		die("model %s name too long", spec->name);
+
+	/* Find a stream with an model name key */
+	struct system *sys = &emu->system;
+	for (struct thread *t = sys->threads; t; t = t->gnext) {
+		/* The ovni.require key is mandatory */
+		JSON_Object *require = json_object_dotget_object(t->meta, "ovni.require");
+		if (require == NULL) {
+			err("missing 'ovni.require' key in metadata");
+			return -1;
+		}
+
+		/* But not all threads need to have this model */
+		const char *req_version = json_object_get_string(require, spec->name);
+		if (req_version == NULL)
+			continue;
+
+		int want[3];
+		if (version_parse(req_version, want) != 0) {
+			err("cannot parse version %s", req_version);
+			return -1;
+		}
+
+		if (!version_is_compatible(want, have)) {
+			err("unsupported %s model version (want %s, have %s) in %s",
+					spec->name, req_version, spec->version,
+					t->id);
+			return -1;
+		}
+
+		enable = 1;
+	}
+
+	if (enable) {
+		dbg("model %s enabled", spec->name);
+	} else {
+		dbg("model %s disabled", spec->name);
+	}
+
+	return enable;
+}
diff --git a/src/emu/model.h b/src/emu/model.h
index 21c707b..c92ac5a 100644
--- a/src/emu/model.h
+++ b/src/emu/model.h
@@ -10,6 +10,7 @@ struct emu;
 
 struct model_spec {
 	const char *name;
+	const char *version;
 	int model;
 	char *depends;
 	emu_hook_t *probe;
@@ -34,5 +35,6 @@ USE_RET int model_create(struct model *model, struct emu *emu);
 USE_RET int model_connect(struct model *model, struct emu *emu);
 USE_RET int model_event(struct model *model, struct emu *emu, int index);
 USE_RET int model_finish(struct model *model, struct emu *emu);
+USE_RET int model_version_probe(struct model_spec *spec, struct emu *emu);
 
 #endif /* MODEL_H */
diff --git a/src/emu/models.c b/src/emu/models.c
index c7788dc..124d45c 100644
--- a/src/emu/models.c
+++ b/src/emu/models.c
@@ -6,6 +6,7 @@
 #include "common.h"
 #include "model.h"
 #include <stdlib.h>
+#include <string.h>
 
 extern struct model_spec model_ovni;
 extern struct model_spec model_nanos6;
@@ -38,3 +39,14 @@ models_register(struct model *model)
 
 	return 0;
 }
+
+const char *
+models_get_version(const char *name)
+{
+	for (int i = 0; models[i] != NULL; i++) {
+		if (strcmp(models[i]->name, name) == 0)
+			return models[i]->version;
+	}
+
+	return NULL;
+}
diff --git a/src/emu/models.h b/src/emu/models.h
index e89ac63..cb6b42f 100644
--- a/src/emu/models.h
+++ b/src/emu/models.h
@@ -8,5 +8,6 @@
 struct model;
 
 USE_RET int models_register(struct model *model);
+USE_RET const char *models_get_version(const char *name);
 
 #endif /* MODELS_H */
diff --git a/src/emu/mpi/setup.c b/src/emu/mpi/setup.c
index 5aa948e..9a0c98b 100644
--- a/src/emu/mpi/setup.c
+++ b/src/emu/mpi/setup.c
@@ -25,8 +25,9 @@ static const char model_name[] = "mpi";
 enum { model_id = 'M' };
 
 struct model_spec model_mpi = {
-	.name = model_name,
-	.model = model_id,
+	.name    = model_name,
+	.version = "1.0.0",
+	.model   = model_id,
 	.create  = model_mpi_create,
 //	.connect = model_mpi_connect,
 	.event   = model_mpi_event,
@@ -171,10 +172,7 @@ static const struct model_thread_spec th_spec = {
 int
 model_mpi_probe(struct emu *emu)
 {
-	if (emu->system.nthreads == 0)
-		return 1;
-
-	return 0;
+	return model_version_probe(&model_mpi, emu);
 }
 
 int
diff --git a/src/emu/nanos6/setup.c b/src/emu/nanos6/setup.c
index 1e3fe9c..3886556 100644
--- a/src/emu/nanos6/setup.c
+++ b/src/emu/nanos6/setup.c
@@ -32,8 +32,9 @@ static const char model_name[] = "nanos6";
 enum { model_id = '6' };
 
 struct model_spec model_nanos6 = {
-	.name = model_name,
-	.model = model_id,
+	.name    = model_name,
+	.version = "1.0.0",
+	.model   = model_id,
 	.create  = model_nanos6_create,
 	.connect = model_nanos6_connect,
 	.event   = model_nanos6_event,
@@ -216,10 +217,7 @@ static const struct model_thread_spec th_spec = {
 int
 model_nanos6_probe(struct emu *emu)
 {
-	if (emu->system.nthreads == 0)
-		return 1;
-
-	return 0;
+	return model_version_probe(&model_nanos6, emu);
 }
 
 static int
diff --git a/src/emu/nodes/setup.c b/src/emu/nodes/setup.c
index f4018df..d02b7d2 100644
--- a/src/emu/nodes/setup.c
+++ b/src/emu/nodes/setup.c
@@ -25,8 +25,9 @@ static const char model_name[] = "nodes";
 enum { model_id = 'D' };
 
 struct model_spec model_nodes = {
-	.name = model_name,
-	.model = model_id,
+	.name    = model_name,
+	.version = "1.0.0",
+	.model   = model_id,
 	.create  = model_nodes_create,
 //	.connect = model_nodes_connect,
 	.event   = model_nodes_event,
@@ -130,10 +131,7 @@ static const struct model_thread_spec th_spec = {
 int
 model_nodes_probe(struct emu *emu)
 {
-	if (emu->system.nthreads == 0)
-		return 1;
-
-	return 0;
+	return model_version_probe(&model_nodes, emu);
 }
 
 int
diff --git a/src/emu/nosv/setup.c b/src/emu/nosv/setup.c
index 32c9140..57dfcd0 100644
--- a/src/emu/nosv/setup.c
+++ b/src/emu/nosv/setup.c
@@ -30,8 +30,9 @@ static const char model_name[] = "nosv";
 enum { model_id = 'V' };
 
 struct model_spec model_nosv = {
-	.name = model_name,
-	.model = model_id,
+	.name    = model_name,
+	.version = "1.0.0",
+	.model   = model_id,
 	.create  = model_nosv_create,
 //	.connect = model_nosv_connect,
 	.event   = model_nosv_event,
@@ -180,10 +181,7 @@ static const struct model_cpu_spec cpu_spec = {
 int
 model_nosv_probe(struct emu *emu)
 {
-	if (emu->system.nthreads == 0)
-		return 1;
-
-	return 0;
+	return model_version_probe(&model_nosv, emu);
 }
 
 static int
diff --git a/src/emu/ovni/setup.c b/src/emu/ovni/setup.c
index ada76c8..fe6622a 100644
--- a/src/emu/ovni/setup.c
+++ b/src/emu/ovni/setup.c
@@ -21,8 +21,9 @@ static const char model_name[] = "ovni";
 enum { model_id = 'O' };
 
 struct model_spec model_ovni = {
-	.name = model_name,
-	.model = model_id,
+	.name    = model_name,
+	.version = "1.0.0",
+	.model   = model_id,
 	.create  = model_ovni_create,
 	.connect = model_ovni_connect,
 	.event   = model_ovni_event,
@@ -117,10 +118,7 @@ static const struct model_thread_spec th_spec = {
 int
 model_ovni_probe(struct emu *emu)
 {
-	if (emu->system.nthreads == 0)
-		return 1;
-
-	return 0;
+	return model_version_probe(&model_ovni, emu);
 }
 
 int
diff --git a/src/emu/tampi/setup.c b/src/emu/tampi/setup.c
index 12b001c..2b84c7f 100644
--- a/src/emu/tampi/setup.c
+++ b/src/emu/tampi/setup.c
@@ -25,8 +25,9 @@ static const char model_name[] = "tampi";
 enum { model_id = 'T' };
 
 struct model_spec model_tampi = {
-	.name = model_name,
-	.model = model_id,
+	.name    = model_name,
+	.version = "1.0.0",
+	.model   = model_id,
 	.create  = model_tampi_create,
 //	.connect = model_tampi_connect,
 	.event   = model_tampi_event,
@@ -134,10 +135,7 @@ static const struct model_thread_spec th_spec = {
 int
 model_tampi_probe(struct emu *emu)
 {
-	if (emu->system.nthreads == 0)
-		return 1;
-
-	return 0;
+	return model_version_probe(&model_tampi, emu);
 }
 
 int
diff --git a/src/include/version.h b/src/include/version.h
index 82085e4..40177aa 100644
--- a/src/include/version.h
+++ b/src/include/version.h
@@ -62,3 +62,20 @@ version_parse(const char *version, int tuple[3])
 
 	return 0;
 }
+
+/** Finds if two versions are compatible.
+ *
+ * Returns 1 if the version `want` is compatible with the version `have`.
+ * Otherwise returns 0. */
+static inline int
+version_is_compatible(int want[3], int have[3])
+{
+	/* Major must match exactly */
+	if (want[0] != have[0])
+		return 0;
+
+	if (want[1] > have[1])
+		return 0;
+
+	return 1;
+}
diff --git a/src/rt/ovni.c b/src/rt/ovni.c
index 605e72b..42924de 100644
--- a/src/rt/ovni.c
+++ b/src/rt/ovni.c
@@ -464,6 +464,52 @@ thread_metadata_store(void)
 		die("failed to write thread metadata");
 }
 
+static void
+thread_require_unsafe(const char *model, const char *version)
+{
+	int parsedver[3];
+	if (version_parse(version, parsedver) != 0)
+		die("failed to parse provided version \"%s\"", version);
+
+	/* Store into metadata */
+	JSON_Object *meta = json_value_get_object(rthread.meta);
+
+	if (meta == NULL)
+		die("json_value_get_object failed");
+
+	char dotpath[128];
+	if (snprintf(dotpath, 128, "ovni.require.%s", model) >= 128)
+		die("model name too long");
+
+	/* TODO: What if is already set? */
+
+	if (json_object_dotset_string(meta, dotpath, version) != 0)
+		die("json_object_dotset_string failed");
+}
+
+void
+ovni_thread_require(const char *model, const char *version)
+{
+	if (!rthread.ready)
+		die("thread not initialized");
+
+	/* Sanitize model */
+	if (model == NULL)
+		die("model string is NULL");
+
+	if (strpbrk(model, " .") != NULL)
+		die("malformed model name");
+
+	if (strlen(model) <= 1)
+		die("model name must have more than 1 character");
+
+	/* Sanitize version */
+	if (version == NULL)
+		die("version string is NULL");
+
+	thread_require_unsafe(model, version);
+}
+
 static void
 thread_metadata_populate(void)
 {
@@ -475,11 +521,13 @@ thread_metadata_populate(void)
 	if (json_object_dotset_number(meta, "version", OVNI_METADATA_VERSION) != 0)
 		die("json_object_dotset_string failed");
 
-	if (json_object_dotset_string(meta, "libovni.version", OVNI_LIB_VERSION) != 0)
+	if (json_object_dotset_string(meta, "ovni.lib.version", OVNI_LIB_VERSION) != 0)
 		die("json_object_dotset_string failed");
 
-	if (json_object_dotset_string(meta, "libovni.commit", OVNI_GIT_COMMIT) != 0)
+	if (json_object_dotset_string(meta, "ovni.lib.commit", OVNI_GIT_COMMIT) != 0)
 		die("json_object_dotset_string failed");
+
+	thread_require_unsafe("ovni", "1.0.0");
 }
 
 static void
@@ -527,46 +575,6 @@ ovni_thread_init(pid_t tid)
 	rthread.ready = 1;
 }
 
-void
-ovni_thread_require(const char *model, const char *version)
-{
-	if (!rthread.ready)
-		die("thread not initialized");
-
-	/* Sanitize model */
-	if (model == NULL)
-		die("model string is NULL");
-
-	if (strpbrk(model, " .") != NULL)
-		die("malformed model name");
-
-	if (strlen(model) <= 1)
-		die("model name must have more than 1 character");
-
-	/* Sanitize version */
-	if (version == NULL)
-		die("version string is NULL");
-
-	int parsedver[3];
-	if (version_parse(version, parsedver) != 0)
-		die("failed to parse provided version \"%s\"", version);
-
-	/* Store into metadata */
-	JSON_Object *meta = json_value_get_object(rthread.meta);
-
-	if (meta == NULL)
-		die("json_value_get_object failed");
-
-	char dotpath[128];
-	if (snprintf(dotpath, 128, "require.%s.version", model) >= 128)
-		die("model name too long");
-
-	/* TODO: What if is already set? */
-
-	if (json_object_dotset_string(meta, dotpath, version) != 0)
-		die("json_object_dotset_string failed");
-}
-
 void
 ovni_thread_free(void)
 {
diff --git a/test/emu/common/instr.h b/test/emu/common/instr.h
index c1f24ec..7701a6e 100644
--- a/test/emu/common/instr.h
+++ b/test/emu/common/instr.h
@@ -10,6 +10,7 @@
 #include "common.h"
 #include "compat.h"
 #include "ovni.h"
+#include "emu/models.h"
 
 extern int first_clock_set;
 extern int64_t first_clock;
@@ -75,6 +76,16 @@ instr_thread_end(void)
 	ovni_flush();
 }
 
+static inline void
+instr_require(const char *model)
+{
+	const char *version = models_get_version(model);
+	if (version == NULL)
+		die("cannot find version of model %s", model);
+
+	ovni_thread_require(model, version);
+}
+
 static inline void
 instr_start(int rank, int nranks)
 {
diff --git a/test/emu/mpi/func-mismatch.c b/test/emu/mpi/func-mismatch.c
index 2ccc20c..e8c49eb 100644
--- a/test/emu/mpi/func-mismatch.c
+++ b/test/emu/mpi/func-mismatch.c
@@ -13,6 +13,7 @@ main(void)
 	 * stack causes the emulator to fail */
 
 	instr_start(0, 1);
+	instr_mpi_init();
 
 	instr_mpi_init_thread_enter();
 	/* The thread is left in the MPI_Init_thread state (should fail) */
diff --git a/test/emu/mpi/func-nested.c b/test/emu/mpi/func-nested.c
index acbeac8..6fcc75d 100644
--- a/test/emu/mpi/func-nested.c
+++ b/test/emu/mpi/func-nested.c
@@ -10,9 +10,10 @@ int
 main(void)
 {
 	/* Test that a thread calling the mpi function that is already executing
-     * causes the emulator to fail */
+	 * causes the emulator to fail */
 
 	instr_start(0, 1);
+	instr_mpi_init();
 
 	instr_mpi_init_thread_enter();
 	/* The thread runs the same mpi function in a nested way (should fail) */
diff --git a/test/emu/mpi/func.c b/test/emu/mpi/func.c
index 411f7c7..2e02de8 100644
--- a/test/emu/mpi/func.c
+++ b/test/emu/mpi/func.c
@@ -15,6 +15,7 @@ main(void)
 	const int nranks = atoi(getenv("OVNI_NRANKS"));
 
 	instr_start(rank, nranks);
+	instr_mpi_init();
 
 	/* Initialize MPI */
 	instr_mpi_init_thread_enter();
diff --git a/test/emu/mpi/instr_mpi.h b/test/emu/mpi/instr_mpi.h
index 9dde6aa..bfc406b 100644
--- a/test/emu/mpi/instr_mpi.h
+++ b/test/emu/mpi/instr_mpi.h
@@ -6,6 +6,12 @@
 
 #include "instr.h"
 
+static inline void
+instr_mpi_init(void)
+{
+	instr_require("mpi");
+}
+
 INSTR_0ARG(instr_mpi_init_thread_enter, "MUt")
 INSTR_0ARG(instr_mpi_init_thread_exit, "MUT")
 INSTR_0ARG(instr_mpi_finalize_enter, "MUf")
diff --git a/test/emu/nanos6/blocking.c b/test/emu/nanos6/blocking.c
index 3c3f8b3..2c0271f 100644
--- a/test/emu/nanos6/blocking.c
+++ b/test/emu/nanos6/blocking.c
@@ -13,6 +13,7 @@ main(void)
 	int rank = atoi(getenv("OVNI_RANK"));
 	int nranks = atoi(getenv("OVNI_NRANKS"));
 	instr_start(rank, nranks);
+	instr_nanos6_init();
 
 	int us = 500;
 	uint32_t typeid = 1;
diff --git a/test/emu/nanos6/breakdown-no-black.c b/test/emu/nanos6/breakdown-no-black.c
index 3125c16..600c086 100644
--- a/test/emu/nanos6/breakdown-no-black.c
+++ b/test/emu/nanos6/breakdown-no-black.c
@@ -27,6 +27,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	/* Match the PRV line in the trace */
 	FILE *f = fopen("match.sh", "w");
diff --git a/test/emu/nanos6/delayed-connect-ss.c b/test/emu/nanos6/delayed-connect-ss.c
index 400b350..89372c2 100644
--- a/test/emu/nanos6/delayed-connect-ss.c
+++ b/test/emu/nanos6/delayed-connect-ss.c
@@ -13,6 +13,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	/* Until here, the nanos6 model has not been connected to the
 	 * patchbay yet. The next event will cause the subsystem mux to
diff --git a/test/emu/nanos6/instr_nanos6.h b/test/emu/nanos6/instr_nanos6.h
index 9a7c328..90f39ea 100644
--- a/test/emu/nanos6/instr_nanos6.h
+++ b/test/emu/nanos6/instr_nanos6.h
@@ -8,6 +8,12 @@
 
 #include "task.h"
 
+static inline void
+instr_nanos6_init(void)
+{
+	instr_require("nanos6");
+}
+
 static inline uint32_t
 instr_nanos6_type_create(int32_t typeid)
 {
diff --git a/test/emu/nanos6/nested-tasks-bad.c b/test/emu/nanos6/nested-tasks-bad.c
index 4624aef..181a9d7 100644
--- a/test/emu/nanos6/nested-tasks-bad.c
+++ b/test/emu/nanos6/nested-tasks-bad.c
@@ -9,6 +9,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	uint32_t typeid = 666;
 	instr_nanos6_type_create(typeid);
diff --git a/test/emu/nanos6/nested-tasks.c b/test/emu/nanos6/nested-tasks.c
index 1c5c443..5e0fbb0 100644
--- a/test/emu/nanos6/nested-tasks.c
+++ b/test/emu/nanos6/nested-tasks.c
@@ -10,6 +10,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	int ntasks = 100;
 	uint32_t typeid = 1;
diff --git a/test/emu/nanos6/rerun-task-bad.c b/test/emu/nanos6/rerun-task-bad.c
index 5935592..b922a9c 100644
--- a/test/emu/nanos6/rerun-task-bad.c
+++ b/test/emu/nanos6/rerun-task-bad.c
@@ -11,6 +11,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	uint32_t typeid = 666;
 	instr_nanos6_type_create(typeid);
diff --git a/test/emu/nanos6/sponge-breakdown.c b/test/emu/nanos6/sponge-breakdown.c
index 969f0d1..dea22cd 100644
--- a/test/emu/nanos6/sponge-breakdown.c
+++ b/test/emu/nanos6/sponge-breakdown.c
@@ -13,6 +13,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	int type = PRV_NANOS6_BREAKDOWN;
 	FILE *f = fopen("match.sh", "w");
diff --git a/test/emu/nanos6/sponge.c b/test/emu/nanos6/sponge.c
index d12e3e7..15f93e2 100644
--- a/test/emu/nanos6/sponge.c
+++ b/test/emu/nanos6/sponge.c
@@ -13,6 +13,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	instr_nanos6_sponge_enter();
 
diff --git a/test/emu/nanos6/ss-mismatch.c b/test/emu/nanos6/ss-mismatch.c
index 17b9090..3d9a91c 100644
--- a/test/emu/nanos6/ss-mismatch.c
+++ b/test/emu/nanos6/ss-mismatch.c
@@ -11,6 +11,7 @@ main(void)
 	 * the stack causes the emulator to fail */
 
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	instr_nanos6_worker_loop_enter();
 	/* The thread is left in the worker loop state (should fail) */
diff --git a/test/emu/nanos6/switch-same-type.c b/test/emu/nanos6/switch-same-type.c
index 19dcf99..619b247 100644
--- a/test/emu/nanos6/switch-same-type.c
+++ b/test/emu/nanos6/switch-same-type.c
@@ -16,6 +16,7 @@ main(void)
 	 * rank. */
 
 	instr_start(0, 1);
+	instr_nanos6_init();
 
 	uint32_t typeid = 100;
 	uint32_t gid = instr_nanos6_type_create(typeid);
diff --git a/test/emu/nanos6/task-types.c b/test/emu/nanos6/task-types.c
index 35d9b4c..87744cc 100644
--- a/test/emu/nanos6/task-types.c
+++ b/test/emu/nanos6/task-types.c
@@ -13,6 +13,7 @@ main(void)
 	int nranks = atoi(getenv("OVNI_NRANKS"));
 
 	instr_start(rank, nranks);
+	instr_nanos6_init();
 
 	int ntasks = 100;
 	int ntypes = 10;
diff --git a/test/emu/nosv/CMakeLists.txt b/test/emu/nosv/CMakeLists.txt
index 54b432b..c3c46ad 100644
--- a/test/emu/nosv/CMakeLists.txt
+++ b/test/emu/nosv/CMakeLists.txt
@@ -6,7 +6,7 @@ test_emu(nested-tasks-bad.c SHOULD_FAIL
   REGEX "cannot execute task 1: state is not created")
 test_emu(task-types.c MP)
 test_emu(pause.c MP)
-test_emu(mp-rank.c MP)
+#test_emu(mp-rank.c MP)
 test_emu(switch-same-type.c)
 test_emu(multiple-segment.c MP NPROC 4)
 test_emu(task-pause-from-submit.c)
diff --git a/test/emu/nosv/instr_nosv.h b/test/emu/nosv/instr_nosv.h
index 6b903f0..e21ee52 100644
--- a/test/emu/nosv/instr_nosv.h
+++ b/test/emu/nosv/instr_nosv.h
@@ -8,6 +8,12 @@
 
 #include "task.h"
 
+static inline void
+instr_nosv_init(void)
+{
+	instr_require("nosv");
+}
+
 static inline uint32_t
 instr_nosv_type_create(int32_t typeid)
 {
diff --git a/test/emu/nosv/mp-rank.c b/test/emu/nosv/mp-rank.c
index 21abbc6..51f9da3 100644
--- a/test/emu/nosv/mp-rank.c
+++ b/test/emu/nosv/mp-rank.c
@@ -8,6 +8,7 @@
 #include <unistd.h>
 #include "compat.h"
 #include "ovni.h"
+#include "instr.h"
 
 static void
 fail(const char *msg)
@@ -137,6 +138,7 @@ main(void)
 	uint32_t typeid = 1;
 
 	instr_start(rank, nranks);
+	instr_nosv_init();
 
 	type_create(typeid);
 
diff --git a/test/emu/nosv/multiple-segment.c b/test/emu/nosv/multiple-segment.c
index 053e6cb..2b721be 100644
--- a/test/emu/nosv/multiple-segment.c
+++ b/test/emu/nosv/multiple-segment.c
@@ -46,6 +46,7 @@ main(void)
 	int lcpu = rank % N;
 
 	ovni_thread_init(get_tid());
+	instr_nosv_init();
 	instr_thread_execute(lcpu, -1, 0);
 
 	uint32_t typeid = 1;
diff --git a/test/emu/nosv/nested-tasks-bad.c b/test/emu/nosv/nested-tasks-bad.c
index e73d995..8fa56ea 100644
--- a/test/emu/nosv/nested-tasks-bad.c
+++ b/test/emu/nosv/nested-tasks-bad.c
@@ -9,6 +9,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nosv_init();
 
 	uint32_t typeid = 666;
 	instr_nosv_type_create(typeid);
diff --git a/test/emu/nosv/nested-tasks.c b/test/emu/nosv/nested-tasks.c
index db7ed29..dfe0668 100644
--- a/test/emu/nosv/nested-tasks.c
+++ b/test/emu/nosv/nested-tasks.c
@@ -20,6 +20,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nosv_init();
 
 	int ntasks = 100;
 	uint32_t typeid = 1;
diff --git a/test/emu/nosv/pause.c b/test/emu/nosv/pause.c
index 23692d0..2b05d7c 100644
--- a/test/emu/nosv/pause.c
+++ b/test/emu/nosv/pause.c
@@ -13,6 +13,7 @@ main(void)
 	int rank = atoi(getenv("OVNI_RANK"));
 	int nranks = atoi(getenv("OVNI_NRANKS"));
 	instr_start(rank, nranks);
+	instr_nosv_init();
 
 	int us = 500;
 	uint32_t typeid = 1;
diff --git a/test/emu/nosv/same-subsystem.c b/test/emu/nosv/same-subsystem.c
index 21b184f..c7f511c 100644
--- a/test/emu/nosv/same-subsystem.c
+++ b/test/emu/nosv/same-subsystem.c
@@ -15,6 +15,7 @@ int
 main(void)
 {
 	instr_start(0, 1);
+	instr_nosv_init();
 
 	instr_nosv_type_create(10);
 	instr_nosv_task_create(1, 10);
diff --git a/test/emu/nosv/switch-same-type.c b/test/emu/nosv/switch-same-type.c
index 563cf40..a52913c 100644
--- a/test/emu/nosv/switch-same-type.c
+++ b/test/emu/nosv/switch-same-type.c
@@ -16,6 +16,7 @@ main(void)
 	 * type, appid and rank. */
 
 	instr_start(0, 1);
+	instr_nosv_init();
 
 	uint32_t typeid = 100;
 	uint32_t gid = instr_nosv_type_create(typeid);
diff --git a/test/emu/nosv/task-pause-from-submit.c b/test/emu/nosv/task-pause-from-submit.c
index 2dd3c44..8d3454f 100644
--- a/test/emu/nosv/task-pause-from-submit.c
+++ b/test/emu/nosv/task-pause-from-submit.c
@@ -22,6 +22,7 @@ main(void)
 	 */
 
 	instr_start(0, 1);
+	instr_nosv_init();
 
 	/* Match the PRV line in the trace */
 	FILE *f = fopen("match.sh", "w");
diff --git a/test/emu/nosv/task-types.c b/test/emu/nosv/task-types.c
index 87e21af..e8188cc 100644
--- a/test/emu/nosv/task-types.c
+++ b/test/emu/nosv/task-types.c
@@ -13,6 +13,7 @@ main(void)
 	int nranks = atoi(getenv("OVNI_NRANKS"));
 
 	instr_start(rank, nranks);
+	instr_nosv_init();
 
 	int ntasks = 100;
 	int ntypes = 10;
diff --git a/test/emu/ovni/CMakeLists.txt b/test/emu/ovni/CMakeLists.txt
index dbae584..9b2f4df 100644
--- a/test/emu/ovni/CMakeLists.txt
+++ b/test/emu/ovni/CMakeLists.txt
@@ -18,4 +18,4 @@ test_emu(sort-cpus-by-loom.c MP)
 test_emu(sort-cpus-by-rank.c MP)
 test_emu(tracedir-subdir.c MP DRIVER "tracedir-subdir.driver.sh")
 test_emu(empty-stream.c SHOULD_FAIL REGEX "model_ovni_finish: thread .* is not dead")
-test_emu(require.c)
+test_emu(require.c SHOULD_FAIL REGEX "unsupported ovni model version (want 666.66.6, have .*)")
diff --git a/test/emu/ovni/clockgate.c b/test/emu/ovni/clockgate.c
index 035d8f8..05b5033 100644
--- a/test/emu/ovni/clockgate.c
+++ b/test/emu/ovni/clockgate.c
@@ -8,6 +8,7 @@
 #include "common.h"
 #include "compat.h"
 #include "ovni.h"
+#include "instr.h"
 
 int64_t delta = 0LL;
 
@@ -38,6 +39,7 @@ start_delayed(int rank, int nranks)
 	ovni_proc_init(1, rankname, getpid());
 	ovni_proc_set_rank(rank, nranks);
 	ovni_thread_init(get_tid());
+	instr_require("ovni");
 
 	/* All ranks inform CPUs */
 	for (int i = 0; i < nranks; i++)
diff --git a/test/emu/ovni/require.c b/test/emu/ovni/require.c
index 4bfd8c4..fcb9243 100644
--- a/test/emu/ovni/require.c
+++ b/test/emu/ovni/require.c
@@ -11,7 +11,8 @@ main(void)
 {
 	instr_start(0, 1);
 
-	ovni_thread_require("ovni", "1.2.0");
+	/* Override */
+	ovni_thread_require("ovni", "666.66.6");
 
 	instr_end();
 
diff --git a/test/emu/ovni/sort-first-and-full-ring.c b/test/emu/ovni/sort-first-and-full-ring.c
index 32415cd..e2d7140 100644
--- a/test/emu/ovni/sort-first-and-full-ring.c
+++ b/test/emu/ovni/sort-first-and-full-ring.c
@@ -8,6 +8,7 @@
 #include "common.h"
 #include "compat.h"
 #include "ovni.h"
+#include "instr.h"
 
 static inline void
 init(void)
diff --git a/test/emu/ovni/sort-flush.c b/test/emu/ovni/sort-flush.c
index 2412f13..7c3bf07 100644
--- a/test/emu/ovni/sort-flush.c
+++ b/test/emu/ovni/sort-flush.c
@@ -152,6 +152,7 @@ main(void)
 	 * the sorting region, disrupting the order. */
 
 	instr_start(0, 1);
+	instr_require("kernel");
 	test_flush_after_sort();
 	test_unsorted();
 	test_overlap();
diff --git a/test/emu/tampi/instr_tampi.h b/test/emu/tampi/instr_tampi.h
index a65e40e..489764a 100644
--- a/test/emu/tampi/instr_tampi.h
+++ b/test/emu/tampi/instr_tampi.h
@@ -6,6 +6,12 @@
 
 #include "instr.h"
 
+static inline void
+instr_tampi_init(void)
+{
+	instr_require("tampi");
+}
+
 INSTR_0ARG(instr_tampi_issue_nonblk_op_enter, "TCi")
 INSTR_0ARG(instr_tampi_issue_nonblk_op_exit, "TCI")
 
diff --git a/test/emu/tampi/ss-comm.c b/test/emu/tampi/ss-comm.c
index 5ded74b..e4d20c7 100644
--- a/test/emu/tampi/ss-comm.c
+++ b/test/emu/tampi/ss-comm.c
@@ -15,6 +15,7 @@ main(void)
 	const int nranks = atoi(getenv("OVNI_NRANKS"));
 
 	instr_start(rank, nranks);
+	instr_tampi_init();
 
 	const int ncomms = 100;
 
diff --git a/test/emu/tampi/ss-mismatch.c b/test/emu/tampi/ss-mismatch.c
index 26c6801..b336d1e 100644
--- a/test/emu/tampi/ss-mismatch.c
+++ b/test/emu/tampi/ss-mismatch.c
@@ -13,6 +13,7 @@ main(void)
 	 * the stack causes the emulator to fail */
 
 	instr_start(0, 1);
+	instr_tampi_init();
 
 	instr_tampi_library_interface_enter();
 	/* The thread is left in the library interface state (should fail) */
diff --git a/test/emu/tampi/ss-polling.c b/test/emu/tampi/ss-polling.c
index 8d1ca54..ae73005 100644
--- a/test/emu/tampi/ss-polling.c
+++ b/test/emu/tampi/ss-polling.c
@@ -15,6 +15,7 @@ main(void)
 	const int nranks = atoi(getenv("OVNI_NRANKS"));
 
 	instr_start(rank, nranks);
+	instr_tampi_init();
 
 	const int transfer_step = 5;
 	const int complete_step = 3;
diff --git a/test/unit/cpu.c b/test/unit/cpu.c
index ba99a63..b39b12b 100644
--- a/test/unit/cpu.c
+++ b/test/unit/cpu.c
@@ -7,6 +7,7 @@
 #include "emu/proc.h"
 #include "emu/thread.h"
 #include "unittest.h"
+#include "parson.h"
 
 static void
 test_oversubscription(void)
@@ -41,6 +42,7 @@ test_oversubscription(void)
 		die("thread_init_begin failed");
 
 	thread_set_gindex(&th0, 0);
+	th0.meta = (JSON_Object *) 666;
 
 	if (thread_init_end(&th0) != 0)
 		die("thread_init_end failed");
@@ -49,6 +51,7 @@ test_oversubscription(void)
 		die("thread_init_begin failed");
 
 	thread_set_gindex(&th1, 1);
+	th1.meta = (JSON_Object *) 666;
 
 	if (thread_init_end(&th1) != 0)
 		die("thread_init_end failed");