diff --git a/src/session_impl.cpp b/src/session_impl.cpp
index 81f7c316c..9e28f04e2 100644
--- a/src/session_impl.cpp
+++ b/src/session_impl.cpp
@@ -38,6 +38,8 @@ POSSIBILITY OF SUCH DAMAGE.
 #include <algorithm>
 #include <cctype>
 #include <algorithm>
+#include <cstdio> // for snprintf
+#include <cinttypes> // for PRId64 et.al.
 
 #if defined TORRENT_DEBUG && !defined TORRENT_DISABLE_INVARIANT_CHECKS
 #include <unordered_set>