Index: src/string.c
==================================================================
--- src/string.c
+++ src/string.c
@@ -25,10 +25,11 @@
  */
 
 #include <stdlib.h>
 #include <stdint.h>
 #include <string.h>
+#include <errno.h>
 
 #include "object.h"
 #include "string.h"
 #include "hash.h"
 
@@ -35,20 +36,39 @@
 struct CFWString {
 	CFWObject obj;
 	char *data;
 	size_t len;
 };
+
+char*
+cfw_strdup(const char *s)
+{
+	char *copy;
+	size_t len;
+
+	len = strlen(s);
+
+	if ((copy = malloc(len + 1)) == NULL) {
+		errno = ENOMEM;
+		return NULL;
+	}
+
+	memcpy(copy, s, len);
+	copy[len] = 0;
+
+	return copy;
+}
 
 static bool
 ctor(void *ptr, va_list args)
 {
 	CFWString *str = ptr;
 	const char *cstr = va_arg(args, const char*);
 
 	if (cstr != NULL) {
 		str->data = NULL;
-		if ((str->data = strdup(cstr)) == NULL)
+		if ((str->data = cfw_strdup(cstr)) == NULL)
 			return false;
 
 		str->len = strlen(cstr);
 	} else {
 		str->data = NULL;
@@ -137,11 +157,11 @@
 bool
 cfw_string_set(CFWString *str, const char *cstr)
 {
 	char *copy;
 
-	if ((copy = strdup(cstr)) == NULL)
+	if ((copy = cfw_strdup(cstr)) == NULL)
 		return false;
 
 	if (str->data != NULL)
 		free(str->data);
 

Index: src/string.h
==================================================================
--- src/string.h
+++ src/string.h
@@ -30,12 +30,13 @@
 #include "class.h"
 #include "range.h"
 
 typedef struct CFWString CFWString;
 extern CFWClass *cfw_string;
+extern char* cfw_strdup(const char*);
 extern const char* cfw_string_c(CFWString*);
 extern size_t cfw_string_len(CFWString*);
 extern bool cfw_string_set(CFWString*, const char*);
 extern bool cfw_string_append(CFWString*, CFWString*);
 extern size_t cfw_string_find(CFWString*, CFWString*, cfw_range_t);
 
 #endif