diff --git a/modules/libcom/src/osi/epicsMutex.h b/modules/libcom/src/osi/epicsMutex.h
index 117767a48..c88f57e74 100644
--- a/modules/libcom/src/osi/epicsMutex.h
+++ b/modules/libcom/src/osi/epicsMutex.h
@@ -41,6 +41,7 @@
 #ifndef epicsMutexh
 #define epicsMutexh
 
+#include "cantProceed.h"
 #include "epicsAssert.h"
 
 #include "libComAPI.h"
@@ -212,9 +213,12 @@ LIBCOM_API epicsMutexLockStatus epicsStdCall epicsMutexLock(
  * This routine does not return if the identifier is invalid.
  * \param ID The mutex identifier.
  **/
-#define epicsMutexMustLock(ID) {                        \
-    epicsMutexLockStatus status = epicsMutexLock(ID);   \
-    assert(status == epicsMutexLockOK);                 \
+#define epicsMutexMustLock(ID) {                            \
+    epicsMutexLockStatus status = epicsMutexLock(ID);       \
+    if(status != epicsMutexLockOK) {                        \
+        cantProceed("epicsMutexMustLock() failed at %s:%d", \
+            __FILE__, __LINE__);                            \
+    }                                                       \
 }
 
 /**\brief Similar to epicsMutexLock() except that the call returns immediately,