diff --git a/src/lib/gcrypt/MD5.hxx b/src/lib/gcrypt/MD5.hxx
index 03bfb0347..8e52fa239 100644
--- a/src/lib/gcrypt/MD5.hxx
+++ b/src/lib/gcrypt/MD5.hxx
@@ -35,6 +35,8 @@
 
 #include <array>
 
+#include <stdint.h>
+
 template<typename T> struct ConstBuffer;
 
 gcc_pure