diff --git a/ompi/mca/osc/pt2pt/osc_pt2pt.h b/ompi/mca/osc/pt2pt/osc_pt2pt.h
index c5d66ca2a3b..bbb35f55629 100644
--- a/ompi/mca/osc/pt2pt/osc_pt2pt.h
+++ b/ompi/mca/osc/pt2pt/osc_pt2pt.h
@@ -121,7 +121,7 @@ struct ompi_osc_pt2pt_peer_t {
     int32_t passive_incoming_frag_count;
 
     /** peer flags */
-    int32_t flags;
+    volatile int32_t flags;
 };
 typedef struct ompi_osc_pt2pt_peer_t ompi_osc_pt2pt_peer_t;
 
@@ -144,11 +144,15 @@ static inline bool ompi_osc_pt2pt_peer_eager_active (ompi_osc_pt2pt_peer_t *peer
 
 static inline void ompi_osc_pt2pt_peer_set_flag (ompi_osc_pt2pt_peer_t *peer, int32_t flag, bool value)
 {
-    if (value) {
-        peer->flags |= flag;
-    } else {
-        peer->flags &= ~flag;
-    }
+    int32_t peer_flags, new_flags;
+    do {
+        peer_flags = peer->flags;
+        if (value) {
+            new_flags = peer_flags | flag;
+        } else {
+            new_flags = peer_flags & ~flag;
+        }
+    } while (!OPAL_ATOMIC_CMPSET_32 (&peer->flags, peer_flags, new_flags));
 }
 
 static inline void ompi_osc_pt2pt_peer_set_locked (ompi_osc_pt2pt_peer_t *peer, bool value)
diff --git a/ompi/mca/osc/pt2pt/osc_pt2pt_sync.h b/ompi/mca/osc/pt2pt/osc_pt2pt_sync.h
index 5e1d9905158..87bd1c45ad2 100644
--- a/ompi/mca/osc/pt2pt/osc_pt2pt_sync.h
+++ b/ompi/mca/osc/pt2pt/osc_pt2pt_sync.h
@@ -74,10 +74,10 @@ struct ompi_osc_pt2pt_sync_t {
     int num_peers;
 
     /** number of synchronization messages expected */
-    int32_t sync_expected;
+    volatile int32_t sync_expected;
 
     /** eager sends are active to all peers in this access epoch */
-    bool eager_send_active;
+    volatile bool eager_send_active;
 
     /** communication has started on this epoch */
     bool epoch_active;
@@ -175,7 +175,7 @@ static inline void ompi_osc_pt2pt_sync_expected (ompi_osc_pt2pt_sync_t *sync)
 static inline void ompi_osc_pt2pt_sync_reset (ompi_osc_pt2pt_sync_t *sync)
 {
     sync->type = OMPI_OSC_PT2PT_SYNC_TYPE_NONE;
-    sync->eager_send_active = 0;
+    sync->eager_send_active = false;
     sync->epoch_active = 0;
     sync->peer_list.peers = NULL;
     sync->sync.pscw.group = NULL;