diff --git a/x_ctypes/src/x_ctypes.c b/x_ctypes/src/x_ctypes.c
index f1d1cd7..dbf30a2 100644
--- a/x_ctypes/src/x_ctypes.c
+++ b/x_ctypes/src/x_ctypes.c
@@ -1,10 +1,10 @@
 #include <stdio.h>
 
 int x_isdigit(const char x){
-	if ( x > 48 && x < 57 ){
+	if ( x >= 48 && x <= 57 ){
 		return 1;
 	}
-	else if ( x > 0 && x < 9 ){
+	else if ( x >= 0 && x <= 9 ){
 		return 1;
 	}