diff --git a/vlib/v/checker/for.v b/vlib/v/checker/for.v
index 91860ca871..ce7280a417 100644
--- a/vlib/v/checker/for.v
+++ b/vlib/v/checker/for.v
@@ -119,9 +119,11 @@ fn (mut c Checker) for_in_stmt(mut node ast.ForInStmt) {
 					}
 					ast.SelectorExpr {
 						root_ident := node.cond.root_ident() or { node.cond.expr as ast.Ident }
-						if !(root_ident.obj as ast.Var).is_mut {
-							c.error('field `$node.cond.field_name` is immutable, it cannot be changed',
-								node.cond.pos)
+						if root_ident.kind != .unresolved {
+							if !(root_ident.obj as ast.Var).is_mut {
+								c.error('field `$node.cond.field_name` is immutable, it cannot be changed',
+									node.cond.pos)
+							}
 						}
 					}
 					else {}
diff --git a/vlib/v/checker/tests/for_in_invalid_identifier.out b/vlib/v/checker/tests/for_in_invalid_identifier.out
new file mode 100644
index 0000000000..79115d7d71
--- /dev/null
+++ b/vlib/v/checker/tests/for_in_invalid_identifier.out
@@ -0,0 +1,13 @@
+vlib/v/checker/tests/for_in_invalid_identifier.vv:2:26: error: undefined ident: `s`
+    1 | fn main() {
+    2 |     for index, mut value in s.statements {
+      |                             ^
+    3 |         println('Hello $index $value')
+    4 |     }
+vlib/v/checker/tests/for_in_invalid_identifier.vv:3:26: error: no known default format for type `void`
+    1 | fn main() {
+    2 |     for index, mut value in s.statements {
+    3 |         println('Hello $index $value')
+      |                                ~~~~~
+    4 |     }
+    5 | }
\ No newline at end of file
diff --git a/vlib/v/checker/tests/for_in_invalid_identifier.vv b/vlib/v/checker/tests/for_in_invalid_identifier.vv
new file mode 100644
index 0000000000..c062fed3d3
--- /dev/null
+++ b/vlib/v/checker/tests/for_in_invalid_identifier.vv
@@ -0,0 +1,5 @@
+fn main() {
+	for index, mut value in s.statements {
+		println('Hello $index $value')
+	}
+}