diff --git a/dtls_debug.c b/dtls_debug.c
index 70c88ff..ad01466 100644
--- a/dtls_debug.c
+++ b/dtls_debug.c
@@ -28,6 +28,8 @@
 #include <arpa/inet.h>
 #endif
 
+#include <string.h>
+
 #ifdef HAVE_TIME_H
 #include <time.h>
 #endif
diff --git a/session.c b/session.c
index 2267d93..346eae5 100644
--- a/session.c
+++ b/session.c
@@ -14,6 +14,8 @@
  *
  *******************************************************************************/
 
+#include <string.h>
+
 #include "session.h"
 
 #ifdef HAVE_ASSERT_H
diff --git a/session.h b/session.h
index 0e05e1a..3aa48c5 100644
--- a/session.h
+++ b/session.h
@@ -17,8 +17,6 @@
 #ifndef _DTLS_SESSION_H_
 #define _DTLS_SESSION_H_
 
-#include <string.h>
-
 #include "tinydtls.h"
 #include "global.h"