diff --git a/Source/charon/logger.c b/Source/charon/logger.c
index e83917288..da0f85c5f 100644
--- a/Source/charon/logger.c
+++ b/Source/charon/logger.c
@@ -29,6 +29,7 @@
 #include <syslog.h>
 #include <stdarg.h>
 #include <string.h>
+#include <stdio.h>
 
 /**
  * Maximum length of al log entry (only used for logger_s.log)