diff --git a/main/file.c b/main/file.c
index 7385b9bc285769e4c7e3ca252699489ef5530ee5..7aa50313699314cd0f0e1ea6c50c9258931c7b46 100644
--- a/main/file.c
+++ b/main/file.c
@@ -546,7 +546,7 @@ 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;