diff --git a/vlib/v/checker/tests/undefined_ident_in_if_guard_err.out b/vlib/v/checker/tests/undefined_ident_in_if_guard_err_a.out
similarity index 59%
rename from vlib/v/checker/tests/undefined_ident_in_if_guard_err.out
rename to vlib/v/checker/tests/undefined_ident_in_if_guard_err_a.out
index 23584a5012..d9ebc58e52 100644
--- a/vlib/v/checker/tests/undefined_ident_in_if_guard_err.out
+++ b/vlib/v/checker/tests/undefined_ident_in_if_guard_err_a.out
@@ -1,4 +1,4 @@
-vlib/v/checker/tests/undefined_ident_in_if_guard_err.vv:6:11: error: undefined variable: `re`
+vlib/v/checker/tests/undefined_ident_in_if_guard_err_a.vv:6:11: error: undefined variable: `re`
     4 |
     5 | fn main() {
     6 |     if re := re.regex_opt('a') {
diff --git a/vlib/v/checker/tests/undefined_ident_in_if_guard_err.vv b/vlib/v/checker/tests/undefined_ident_in_if_guard_err_a.vv
similarity index 100%
rename from vlib/v/checker/tests/undefined_ident_in_if_guard_err.vv
rename to vlib/v/checker/tests/undefined_ident_in_if_guard_err_a.vv
diff --git a/vlib/v/checker/tests/undefined_ident_in_if_guard_err_b.out b/vlib/v/checker/tests/undefined_ident_in_if_guard_err_b.out
new file mode 100644
index 0000000000..a6d6e0f0ea
--- /dev/null
+++ b/vlib/v/checker/tests/undefined_ident_in_if_guard_err_b.out
@@ -0,0 +1,6 @@
+vlib/v/checker/tests/undefined_ident_in_if_guard_err_b.vv:3:17: error: undefined variable: `id`
+    1 | fn main(){
+    2 |     items := {'a': 'A'}
+    3 |     if id := items[id] {} else {}
+      |                    ~~
+    4 | }
diff --git a/vlib/v/checker/tests/undefined_ident_in_if_guard_err_b.vv b/vlib/v/checker/tests/undefined_ident_in_if_guard_err_b.vv
new file mode 100644
index 0000000000..7c344dc5f7
--- /dev/null
+++ b/vlib/v/checker/tests/undefined_ident_in_if_guard_err_b.vv
@@ -0,0 +1,4 @@
+fn main(){
+	items := {'a': 'A'}
+	if id := items[id] {} else {}
+}
diff --git a/vlib/v/parser/assign.v b/vlib/v/parser/assign.v
index 52e6004c2e..9bb2594c7b 100644
--- a/vlib/v/parser/assign.v
+++ b/vlib/v/parser/assign.v
@@ -59,6 +59,10 @@ fn (mut p Parser) check_undefined_variables(exprs []ast.Expr, val ast.Expr) ? {
 				p.check_undefined_variables(exprs, arg.expr)?
 			}
 		}
+		ast.IndexExpr {
+			p.check_undefined_variables(exprs, val.left)?
+			p.check_undefined_variables(exprs, val.index)?
+		}
 		ast.InfixExpr {
 			p.check_undefined_variables(exprs, val.left)?
 			p.check_undefined_variables(exprs, val.right)?
@@ -155,6 +159,10 @@ fn (mut p Parser) check_undefined_variables_by_names(names []string, val ast.Exp
 				p.check_undefined_variables_by_names(names, arg.expr)?
 			}
 		}
+		ast.IndexExpr {
+			p.check_undefined_variables_by_names(names, val.left)?
+			p.check_undefined_variables_by_names(names, val.index)?
+		}
 		ast.InfixExpr {
 			p.check_undefined_variables_by_names(names, val.left)?
 			p.check_undefined_variables_by_names(names, val.right)?