diff --git a/lib/file_utils.cpp b/lib/file_utils.cpp
index 375e9c7dd..75dd3d4f0 100644
--- a/lib/file_utils.cpp
+++ b/lib/file_utils.cpp
@@ -21,6 +21,7 @@
 #include <cstring>
 #include <sstream>
 #include <string>
+#include <cstdint>
 
 #include <minizinc/_thirdparty/b64/decode.h>
 #include <minizinc/_thirdparty/b64/encode.h>