diff --git a/src/steamnetworkingsockets/steamnetworkingsockets_certstore.cpp b/src/steamnetworkingsockets/steamnetworkingsockets_certstore.cpp
index f60e9cec..781104c4 100644
--- a/src/steamnetworkingsockets/steamnetworkingsockets_certstore.cpp
+++ b/src/steamnetworkingsockets/steamnetworkingsockets_certstore.cpp
@@ -8,6 +8,7 @@
 
 #include <time.h>
 #include <ostream>
+#include <crypto.h>
 #include <crypto_25519.h>
 #include "steamnetworkingsockets_certstore.h"
 #include <tier1/utlhashmap.h>