diff --git a/require-ess/src/require.c b/require-ess/src/require.c
index 2803e9296e0deb18fd6c215890c0a65c9b57b6b4..3c95a76e3862dabc8596ed405eafbda446703fef 100644
--- a/require-ess/src/require.c
+++ b/require-ess/src/require.c
@@ -637,7 +637,8 @@ static int compareVersions(const char *found, const char *request,
   semver_t *sv_found, *sv_request;
   int match;
 
-  debug("require: compareVersions(found=%s, request=%s)\n", found, request);
+  debug("require: compareVersions(found=%s, request=%s)\n", found,
+        request ? request : "");
 
   if (request == NULL || request[0] == 0) {
     debug("require: compareVersions: MATCH empty version requested\n");
@@ -1020,7 +1021,7 @@ static int require_priv(
           /* Look for highest matching version. */
           if (requireDebug)
             printf("require: checking version %s against required %s\n",
-                   currentFilename, version);
+                   currentFilename, version ? version : "");
 
           switch ((status = compareVersions(currentFilename, version, FALSE))) {
             case MATCH: /* all given numbers match. */
@@ -1029,7 +1030,7 @@ static int require_priv(
 
               if (requireDebug)
                 printf("require: %s %s may match %s\n", module, currentFilename,
-                       version);
+                       version ? version : "");
 
               /* Check if it has our EPICS version and architecture. */
               /* Even if it has no library, at least it has a dep file in the