diff --git a/src/rt/ovni.c b/src/rt/ovni.c
index 6157548..1bac96c 100644
--- a/src/rt/ovni.c
+++ b/src/rt/ovni.c
@@ -5,6 +5,8 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <limits.h>
+#include <stdatomic.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -19,6 +21,13 @@
 #include "version.h"
 #include "utlist.h"
 
+enum {
+	ST_UNINIT = 0,
+	ST_INIT,
+	ST_READY,
+	ST_GONE,
+};
+
 struct ovni_rcpu {
 	int index;
 	int phyid;
@@ -73,8 +82,7 @@ struct ovni_rproc {
 	int rank;
 	int nranks;
 
-	int ready;
-	int finished;
+	atomic_int st;
 
 	JSON_Value *meta;
 };
@@ -171,8 +179,8 @@ ovni_add_cpu(int index, int phyid)
 	if (phyid < 0)
 		die("cannot use negative CPU id %d", phyid);
 
-	if (!rproc.ready)
-		die("process not yet initialized");
+	if (rproc.st != ST_READY)
+		die("process not ready");
 
 	if (!rthread.ready)
 		die("thread not yet initialized");
@@ -190,8 +198,8 @@ ovni_add_cpu(int index, int phyid)
 void
 ovni_proc_set_rank(int rank, int nranks)
 {
-	if (!rproc.ready)
-		die("process not yet initialized");
+	if (rproc.st != ST_READY)
+		die("process not ready");
 
 	rproc.rank_set = 1;
 	rproc.rank = rank;
@@ -237,13 +245,19 @@ create_proc_dir(const char *loom, int pid)
 void
 ovni_proc_init(int app, const char *loom, int pid)
 {
-	if (rproc.ready)
-		die("pid %d already initialized", pid);
+	/* Protect against two threads calling at the same time */
+	int st = ST_UNINIT;
+	bool was_uninit = atomic_compare_exchange_strong(&rproc.st,
+			&st, ST_INIT);
 
-	if (rproc.finished)
-		die("pid %d has finished, cannot init again", pid);
-
-	memset(&rproc, 0, sizeof(rproc));
+	if (!was_uninit) {
+		if (st == ST_INIT)
+			die("pid %d already being initialized", pid);
+		else if (st == ST_READY)
+			die("pid %d already initialized", pid);
+		else if (st == ST_GONE)
+			die("pid %d has finished, cannot init again", pid);
+	}
 
 	if (strlen(loom) >= OVNI_MAX_HOSTNAME)
 		die("loom name too long: %s", loom);
@@ -255,7 +269,7 @@ ovni_proc_init(int app, const char *loom, int pid)
 
 	create_proc_dir(loom, pid);
 
-	rproc.ready = 1;
+	rproc.st = ST_READY;
 }
 
 static int
@@ -353,18 +367,19 @@ try_clean_dir(const char *dir)
 void
 ovni_proc_fini(void)
 {
-	if (!rproc.ready)
-		die("process not initialized");
+	/* Protect against two threads calling at the same time */
+	int st = ST_READY;
+	bool was_ready = atomic_compare_exchange_strong(&rproc.st,
+			&st, ST_GONE);
+
+	if (!was_ready)
+		die("process not ready");
 
 	if (rproc.move_to_final) {
 		try_clean_dir(rproc.procdir);
 		try_clean_dir(rproc.loomdir);
 		try_clean_dir(rproc.tmpdir);
 	}
-
-	/* Mark the process no longer ready */
-	rproc.finished = 1;
-	rproc.ready = 0;
 }
 
 static void
@@ -516,8 +531,8 @@ ovni_thread_init(pid_t tid)
 	if (tid == 0)
 		die("cannot use tid=%d", tid);
 
-	if (!rproc.ready)
-		die("process not yet initialized");
+	if (rproc.st != ST_READY)
+		die("process not ready");
 
 	memset(&rthread, 0, sizeof(rthread));
 
@@ -751,8 +766,8 @@ ovni_flush(void)
 	if (!rthread.ready)
 		die("thread is not initialized");
 
-	if (!rproc.ready)
-		die("process is not initialized");
+	if (rproc.st != ST_READY)
+		die("process not ready");
 
 	ovni_ev_set_clock(&pre, ovni_clock_now());
 	ovni_ev_set_mcv(&pre, "OF[");