diff --git a/src/language/lexer.ts b/src/language/lexer.ts
index 21e872522f..c6f24092e5 100644
--- a/src/language/lexer.ts
+++ b/src/language/lexer.ts
@@ -489,12 +489,11 @@ function readDigits(lexer: Lexer, start: number, firstCode: number): number {
   }
 
   const body = lexer.source.body;
-  let position = start;
-  let code = firstCode;
+  let position = start + 1; // +1 to skip first firstCode
 
-  do {
-    code = body.charCodeAt(++position);
-  } while (isDigit(code));
+  while (isDigit(body.charCodeAt(position))) {
+    ++position;
+  }
 
   return position;
 }