diff --git a/include/polarssl/error.h b/include/polarssl/error.h
index b642c08..da3ef3d 100644
--- a/include/polarssl/error.h
+++ b/include/polarssl/error.h
@@ -24,7 +24,7 @@
 #ifndef POLARSSL_ERROR_H
 #define POLARSSL_ERROR_H
 
-#include <string.h>
+#include <stddef.h>
 
 /**
  * Error code layout.