diff --git a/src/scanner.d b/src/scanner.d
index cd715ba..076a667 100644
--- a/src/scanner.d
+++ b/src/scanner.d
@@ -11,9 +11,9 @@ private bool isAlphaNum_(dchar c) => c.isAlphaNum || c == '_';
 class Scanner {
 	private string source;
 	private Token[] tokens;
-	private int start = 0;
-	private int current = 0;
-	private int line = 1;
+	private uint start = 0;
+	private uint current = 0;
+	private uint line = 1;
 
 	this(string source){
 		this.source = source;