diff --git a/x_string/src/x_string.c b/x_string/src/x_string.c
index 01d3436..4c75ae5 100644
--- a/x_string/src/x_string.c
+++ b/x_string/src/x_string.c
@@ -32,9 +32,9 @@ void x_strcpy(char* dest, char* src, const int size_dest){
 // compare two strings
 // return 0 if equal to eachother
 // return -1 if not
-int x_strcmp (char* str1, char* str2){
-	char* ptr1 = str1;
-	char* ptr2 = str2;
+int x_strcmp (const char* str1, const char* str2){
+	const char* ptr1 = str1;
+	const char* ptr2 = str2;
 
 	while(*ptr1 != '\0' && *ptr2 != '\0'){
 		if(*ptr1 != *ptr2){
diff --git a/x_string/src/x_string.h b/x_string/src/x_string.h
index c3618d9..8ccf9d3 100644
--- a/x_string/src/x_string.h
+++ b/x_string/src/x_string.h
@@ -3,7 +3,7 @@
 
 int x_strlen(char*);
 void x_strcpy(char*, char*, const int);
-int x_strcmp(char*, char*);
+int x_strcmp(const char*, const char*);
 char* x_strconcat(char*, char*);
 
 #endif