diff --git a/third_party/SPIRV-Tools/tools/util/flags.cpp b/third_party/SPIRV-Tools/tools/util/flags.cpp
index 6198e4b..9c99677 100644
--- a/third_party/SPIRV-Tools/tools/util/flags.cpp
+++ b/third_party/SPIRV-Tools/tools/util/flags.cpp
@@ -15,6 +15,7 @@
 #include "flags.h"
 
 #include <algorithm>
+#include <cerrno>
 #include <cstdlib>
 #include <cstring>
 #include <iostream>