diff --git a/src/sym.c b/src/sym.c
index 35fb268..42fb463 100644
--- a/src/sym.c
+++ b/src/sym.c
@@ -232,9 +232,11 @@ const char* symTagGetStr (symTag tag) {
     else if (tag == symParam) return "parameter";
     else {
         char* str = malloc(logi(tag, 10)+2);
-        sprintf(str, "%d", tag);
-        debugErrorUnhandled("symTagGetStr", "symbol tag", str);
-        free(str);
+        if (str) {
+            sprintf(str, "%d", tag);
+            debugErrorUnhandled("symTagGetStr", "symbol tag", str);
+            free(str);
+        }
         return "<unhandled>";
     }
 }
@@ -246,9 +248,11 @@ const char* storageTagGetStr (storageTag tag) {
     else if (tag == storageExtern) return "storageExtern";
     else {
         char* str = malloc(logi(tag, 10)+2);
-        sprintf(str, "%d", tag);
-        debugErrorUnhandled("storageTagGetStr", "storage tag", str);
-        free(str);
+        if (str) {
+            sprintf(str, "%d", tag);
+            debugErrorUnhandled("storageTagGetStr", "storage tag", str);
+            free(str);
+        }
         return "<undefined>";
     }
 }