diff --git a/include/r3.h b/include/r3.h
index dc7cbda..fe1926d 100644
--- a/include/r3.h
+++ b/include/r3.h
@@ -14,6 +14,7 @@
 #include <stdbool.h>
 #include "r3_define.h"
 #include "str_array.h"
+#include "r3_str.h"
 
 #ifdef __cplusplus
 extern "C" {
diff --git a/include/r3_str.h b/include/r3_str.h
index b44ff7f..1243697 100644
--- a/include/r3_str.h
+++ b/include/r3_str.h
@@ -7,8 +7,9 @@
 #ifndef STR_H
 #define STR_H
 
-#include "r3.h"
-#include "config.h"
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 char * r3_slug_compile(const char * str, int len);
 
@@ -51,6 +52,9 @@ char *strdup(const char *s);
 char *strndup(const char *s, int n);
 #endif
 
+#ifdef __cplusplus
+}
+#endif
 
 #endif /* !STR_H */