diff --git a/hiredis.c b/hiredis.c
index c0968ed..a3b3edd 100644
--- a/hiredis.c
+++ b/hiredis.c
@@ -485,6 +485,8 @@ int redisvFormatCommand(char **target, const char *format, va_list ap) {
 
             touched = 1;
             c++;
+            if (*c == '\0')
+                break;
         }
         c++;
     }