diff --git a/sds.c b/sds.c
index 0af9c67..9226799 100644
--- a/sds.c
+++ b/sds.c
@@ -178,6 +178,7 @@ sds sdscatvprintf(sds s, const char *fmt, va_list ap) {
         buf[buflen-2] = '\0';
         va_copy(cpy,ap);
         vsnprintf(buf, buflen, fmt, cpy);
+        va_end(cpy);
         if (buf[buflen-2] != '\0') {
             free(buf);
             buflen *= 2;