diff --git a/x_string/src/x_string.c b/x_string/src/x_string.c
index 20d1674..39c4e3d 100644
--- a/x_string/src/x_string.c
+++ b/x_string/src/x_string.c
@@ -64,7 +64,7 @@ char* x_strconcat(char* str1, char* str2){
 
 	int len1 = x_strlen(str1);
 	int len2 = x_strlen(str2);
-	int new_length = len1 + len2;
+	int new_length = len1 + len2 + 1;
 
 	new_string = malloc( sizeof(*new_string) * new_length );
 	x_strcpy(new_string, str1, new_length);