diff --git a/src/libCom/osi/os/RTEMS/osdSpin.c b/src/libCom/osi/os/RTEMS/osdSpin.c
index 8e6a2096c..1d5a1d108 100644
--- a/src/libCom/osi/os/RTEMS/osdSpin.c
+++ b/src/libCom/osi/os/RTEMS/osdSpin.c
@@ -30,8 +30,7 @@
 
 #include <stdlib.h>
 #include <rtems.h>
-
-#include <epicsAssert.h>
+#include <cantProceed.h>
 
 #include "epicsSpin.h"
 
@@ -61,7 +60,17 @@ void epicsSpinLock(epicsSpinId spin) {
     rtems_interrupt_disable (level);
     _Thread_Disable_dispatch();
     spin->level = level;
-    assert(!spin->locked);
+    if(spin->locked) {
+        rtems_interrupt_enable (level);
+        _Thread_Enable_dispatch();
+        if(!rtems_interrupt_is_in_progress()) {
+            printk("Deadlock in epicsSpinLock(%p).  Either recursive lock, missing unlock, or locked by sleeping thread.", spin);
+            cantProceed(NULL);
+        } else {
+            printk("epicsSpinLock(%p) failure in ISR.  Either recursive lock, missing unlock, or locked by sleeping thread.\n", spin);
+        }
+        return;
+    }
     spin->locked = 1;
 }
 
@@ -72,7 +81,10 @@ int epicsSpinTryLock(epicsSpinId spin) {
 
 void epicsSpinUnlock(epicsSpinId spin) {
     rtems_interrupt_level level = spin->level;
-    assert(spin->locked);
+    if(!spin->locked) {
+        printk("epicsSpinUnlock(%p) failure.  lock not taken\n", spin);
+        return;
+    }
     spin->level = spin->locked = 0;
     rtems_interrupt_enable (level);
     _Thread_Enable_dispatch();
diff --git a/src/libCom/osi/os/vxWorks/osdSpin.c b/src/libCom/osi/os/vxWorks/osdSpin.c
index 990453124..06cb73c63 100644
--- a/src/libCom/osi/os/vxWorks/osdSpin.c
+++ b/src/libCom/osi/os/vxWorks/osdSpin.c
@@ -56,7 +56,16 @@ void epicsSpinLock(epicsSpinId spin) {
     int key = intLock();
     if(!intContext())
         taskLock();
-    assert(!spin->locked);
+    if(spin->locked) {
+        intUnlock(key);
+        if(!intContext()) {
+            taskUnlock();
+            cantProceed("Deadlock in epicsSpinLock().  Either recursive lock, missing unlock, or locked by sleeping thread.");
+        } else {
+            epicsInterruptContextMessage("epicsSpinLock() failure in ISR.  Either recursive lock, missing unlock, or locked by sleeping thread.\n");
+        }
+        return;
+    }
     spin->key = key;
     spin->locked = 1;
 }
@@ -68,7 +77,9 @@ int epicsSpinTryLock(epicsSpinId spin) {
 
 void epicsSpinUnlock(epicsSpinId spin) {
     int key = spin->key;
-    assert(spin->locked);
+    if(!spin->locked) {
+        epicsInterruptContextMessage("epicsSpinUnlock() failure.  lock not taken\n");
+    }
     spin->key = spin->locked = 0;
     intUnlock(key);
     if(!intContext())