diff --git a/src/fastlock.cpp b/src/fastlock.cpp
index 7a946fa8f..c74ca8358 100644
--- a/src/fastlock.cpp
+++ b/src/fastlock.cpp
@@ -42,6 +42,7 @@
 #endif
 #include <string.h>
 #include <stdarg.h>
+#include <stdio.h>
 
 #ifdef __APPLE__
 #include <TargetConditionals.h>