diff --git a/src/memory.c b/src/memory.c
index 5b52e99..362c346 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -17,6 +17,7 @@
 */
 
 #include "rjp_internal.h"
+#include "strings.h"
 
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/output.c b/src/output.c
index 3967ea9..2aaa78c 100644
--- a/src/output.c
+++ b/src/output.c
@@ -22,6 +22,7 @@
 #include "rjp.h"
 #include "rjp_internal.h"
 #include "memory.h"
+#include "strings.h"
 
 #include <string.h> //strlen
 #include <stdio.h> //sprintf