diff --git a/include/ovni.h b/include/ovni.h
index 3034ab5..b7bcb47 100644
--- a/include/ovni.h
+++ b/include/ovni.h
@@ -31,6 +31,8 @@ typedef struct json_value_t JSON_Value;
 #define OVNI_STREAM_VERSION 1
 #define OVNI_MODEL_VERSION "O1 V1 T1 M1 D1 K1 61"
 
+#define OVNI_STREAM_EXT ".obs"
+
 /* Follow https://semver.org rules for versioning */
 #define OVNI_LIB_VERSION "1.0.0"
 
diff --git a/src/emu/trace.c b/src/emu/trace.c
index 4826a93..3d51c89 100644
--- a/src/emu/trace.c
+++ b/src/emu/trace.c
@@ -75,7 +75,7 @@ cb_nftw(const char *fpath, const struct stat *sb,
 	if (typeflag != FTW_F)
 		return 0;
 
-	if (!has_suffix(fpath, ".ovnistream"))
+	if (!has_suffix(fpath, OVNI_STREAM_EXT))
 		return 0;
 
 	return load_stream(cur_trace, fpath);
diff --git a/src/rt/ovni.c b/src/rt/ovni.c
index 7c97f26..c9fbb84 100644
--- a/src/rt/ovni.c
+++ b/src/rt/ovni.c
@@ -61,12 +61,12 @@ create_trace_stream(void)
 {
 	char path[PATH_MAX];
 
-	int written = snprintf(path, PATH_MAX, "%s/thread.%d.ovnistream",
-			rproc.procdir, rthread.tid);
+	int written = snprintf(path, PATH_MAX, "%s/thread.%d%s",
+			rproc.procdir, rthread.tid, OVNI_STREAM_EXT);
 
 	if (written >= PATH_MAX)
-		die("thread trace path too long: %s/thread.%d.ovnistream\n",
-				rproc.procdir, rthread.tid);
+		die("thread trace path too long: %s/thread.%d%s\n",
+				rproc.procdir, rthread.tid, OVNI_STREAM_EXT);
 
 	rthread.streamfd = open(path, O_WRONLY | O_CREAT, 0644);
 
diff --git a/test/unit/cpu.c b/test/unit/cpu.c
index f9b789d..f1e0979 100644
--- a/test/unit/cpu.c
+++ b/test/unit/cpu.c
@@ -29,7 +29,7 @@ test_oversubscription(void)
 
 	struct thread th0, th1;
 
-	if (thread_init_begin(&th0, &proc, "loom.0/proc.0/thread.0.ovnistream") != 0)
+	if (thread_init_begin(&th0, &proc, "loom.0/proc.0/thread.0.obs") != 0)
 		die("thread_init_begin failed");
 
 	thread_set_gindex(&th0, 0);
@@ -37,7 +37,7 @@ test_oversubscription(void)
 	if (thread_init_end(&th0) != 0)
 		die("thread_init_end failed");
 
-	if (thread_init_begin(&th1, &proc, "loom.1/proc.1/thread.1.ovnistream") != 0)
+	if (thread_init_begin(&th1, &proc, "loom.1/proc.1/thread.1.obs") != 0)
 		die("thread_init_begin failed");
 
 	thread_set_gindex(&th1, 1);