diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
index 54fcb2b830d..339ea77509a 100644
--- a/src/cmd/compile/internal/inline/inl.go
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -1194,6 +1194,8 @@ func (subst *inlsubst) clovar(n *ir.Name) *ir.Name {
 	case *ir.AssignStmt, *ir.AssignListStmt:
 		// Mark node for reassignment at the end of inlsubst.node.
 		m.Defn = &subst.defnMarker
+	case *ir.TypeSwitchGuard:
+		// TODO(mdempsky): Set m.Defn properly. See discussion on #45743.
 	default:
 		base.FatalfAt(n.Pos(), "unexpected Defn: %+v", defn)
 	}
diff --git a/test/fixedbugs/issue45743.go b/test/fixedbugs/issue45743.go
new file mode 100644
index 00000000000..0b30e0f2a4d
--- /dev/null
+++ b/test/fixedbugs/issue45743.go
@@ -0,0 +1,20 @@
+// compile
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func fn() func(interface{}) {
+	return func(o interface{}) {
+		switch v := o.(type) {
+		case *int:
+			*v = 1
+		}
+	}
+}
+
+func main() {
+	fn()
+}