diff --git a/du1/program.c b/du1/program.c
index e9d8420..ba48d8d 100644
--- a/du1/program.c
+++ b/du1/program.c
@@ -12,10 +12,10 @@ while(r != EOF){
 		counter++;
 	}
 
-	if(r >= 64 && r <= 91){
+	if(r >= 'a' && r <= 'z'){
 	r = r + 32;
 	}
-	else if(r >= 96 && r <= 123){
+	else if(r >= 'A' && r <= 'Z'){
 		r = r - 32;
 	}
 putchar(r);