diff --git a/src/gencode.js b/src/gencode.js
index 62f6020..fa3d683 100644
--- a/src/gencode.js
+++ b/src/gencode.js
@@ -422,7 +422,7 @@ function genConstrain(ctx, ast) {
     if (ctx.error) return;
     const b = gen(ctx, ast.values[1]);
     if (ctx.error) return;
-    const strErr = ast.fileName +": "+ast.first_line;
+    const strErr = ast.fileName + ":" + ast.first_line + ":" + ast.first_column;
     return `ctx.assert(${a}, ${b}, \"${strErr}\")`;
 }