diff --git a/client/cmdhficlass.c b/client/cmdhficlass.c
index 59b0ddc3..a169e827 100644
--- a/client/cmdhficlass.c
+++ b/client/cmdhficlass.c
@@ -283,8 +283,12 @@ int CmdHFiClassELoad(const char *Cmd) {
 	long fsize = ftell(f);
 	fseek(f, 0, SEEK_SET);
 
-	uint8_t *dump = malloc(fsize);
+	if (fsize < 0) {
+		PrintAndLog("Error, when getting filesize");
+		return 1;
+	}
 
+	uint8_t *dump = malloc(fsize);
 
 	size_t bytes_read = fread(dump, 1, fsize, f);
 	fclose(f);