diff --git a/modules/libcom/src/misc/cantProceed.c b/modules/libcom/src/misc/cantProceed.c
index 80e26f8f6..47b928da3 100644
--- a/modules/libcom/src/misc/cantProceed.c
+++ b/modules/libcom/src/misc/cantProceed.c
@@ -24,7 +24,7 @@ LIBCOM_API void * callocMustSucceed(size_t count, size_t size, const char *msg)
     void * mem = NULL;
     if (count > 0 && size > 0) {
         while ((mem = calloc(count, size)) == NULL) {
-            errlogPrintf("%s: callocMustSucceed(%lu, %lu) - calloc failed\n",
+            errlogPrintf("%s: callocMustSucceed(%lu, %lu) - " ERL_ERROR " calloc failed\n",
                     msg, (unsigned long)count, (unsigned long)size);
             errlogPrintf("Thread %s (%p) suspending.\n",
                     epicsThreadGetNameSelf(), (void *)epicsThreadGetIdSelf());
@@ -40,7 +40,7 @@ LIBCOM_API void * mallocMustSucceed(size_t size, const char *msg)
     void * mem = NULL;
     if (size > 0) {
         while ((mem = malloc(size)) == NULL) {
-            errlogPrintf("%s: mallocMustSucceed(%lu) - malloc failed\n",
+            errlogPrintf("%s: mallocMustSucceed(%lu) - " ERL_ERROR " malloc failed\n",
                 msg, (unsigned long)size);
             errlogPrintf("Thread %s (%p) suspending.\n",
                     epicsThreadGetNameSelf(), (void *)epicsThreadGetIdSelf());
diff --git a/modules/libcom/src/misc/cantProceed.h b/modules/libcom/src/misc/cantProceed.h
index 0232a8611..f9559b14c 100644
--- a/modules/libcom/src/misc/cantProceed.h
+++ b/modules/libcom/src/misc/cantProceed.h
@@ -56,18 +56,24 @@ LIBCOM_API void cantProceed(
  * gracefully when memory runs out.
  */
 /** @{ */
-/** \brief A calloc() that never returns NULL.
+/** \brief A calloc() which suspends on error.
  * \param count Number of objects.
  * \param size Size of each object.
- * \param errorMessage What this memory is needed for.
- * \return Pointer to zeroed allocated memory.
+ * \param errorMessage Context added to logged error message
+ * \return Pointer to zeroed allocated memory.  Should later be free() d
+ *
+ * Will always return NULL for a zero length allocation.
+ * Will never return NULL otherwise.
  */
 LIBCOM_API void * callocMustSucceed(size_t count, size_t size,
     const char *errorMessage);
-/** \brief A malloc() that never returns NULL.
+/** \brief A malloc() which suspends on error.
  * \param size Size of block to allocate.
- * \param errorMessage What this memory is needed for.
- * \return Pointer to allocated memory.
+ * \param errorMessage Context added to logged error message
+ * \return Pointer to allocated memory.  Should later be free() d
+ *
+ * Will always return NULL for a zero length allocation.
+ * Will never return NULL otherwise.
  */
 LIBCOM_API void * mallocMustSucceed(size_t size, const char *errorMessage);
 /** @} */