diff --git a/fuzz/cmark-fuzz.c b/fuzz/cmark-fuzz.c
index b29063252..33ce23655 100644
--- a/fuzz/cmark-fuzz.c
+++ b/fuzz/cmark-fuzz.c
@@ -34,6 +34,10 @@ int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
       case 1: {
         FILE *file = fmemopen((void *) markdown, markdown_size, "r");
+        if (file == NULL) {
+          perror("fmemopen");
+          abort();
+        }
         doc = cmark_parse_file(file, options);
         fclose(file);
         break;