diff --git a/client/src/preferences.c b/client/src/preferences.c
index 1e0b59297..9d482a1f5 100644
--- a/client/src/preferences.c
+++ b/client/src/preferences.c
@@ -122,6 +122,7 @@ int preferences_save(void) {
     char* backupFilename = (char *)calloc(fnLen, sizeof(uint8_t));
     if (backupFilename == NULL) {
         PrintAndLogEx(ERR, "failed to allocate memory");
+        free(fn);
         return PM3_EMALLOC;
     }
     snprintf(backupFilename, fnLen, "%s.bak", fn);