diff --git a/main/file.c b/main/file.c
index 187209dc6b..2645b0bbab 100644
--- a/main/file.c
+++ b/main/file.c
@@ -566,7 +566,7 @@ struct ast_filestream *ast_openstream_full(struct ast_channel *chan, const char
 	}
 	if (preflang == NULL)
 		preflang = "";
-	buflen = strlen(preflang) + strlen(filename) + 2;
+	buflen = strlen(preflang) + strlen(filename) + 4;
 	buf = alloca(buflen);
 	if (buf == NULL)
 		return NULL;