@@ -217,10 +217,13 @@
 
 bool
 cfw_string_append(CFWString *str, CFWString *append)
 {
 	char *new;
+
+	if (append == NULL)
+		return true;
 
 	if ((new = realloc(str->data, str->len + append->len + 1)) == NULL)
 		return false;
 
 	memcpy(new + str->len, append->data, append->len);
@@ -233,12 +236,17 @@
 }
 
 bool
 cfw_string_append_c(CFWString *str, const char *append)
 {
-	size_t append_len = strlen(append);
 	char *new;
+	size_t append_len;
+
+	if (append == NULL)
+		return true;
+
+	append_len = strlen(append);
 
 	if ((new = realloc(str->data, str->len + append_len + 1)) == NULL)
 		return false;
 
 	memcpy(new + str->len, append, append_len);