diff --git a/src/go/types/lookup.go b/src/go/types/lookup.go
index 9c7bfd4bb9..3e89b6cc2b 100644
--- a/src/go/types/lookup.go
+++ b/src/go/types/lookup.go
@@ -327,11 +327,15 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 				return m, f
 			}
 
+			// both methods must have the same number of type parameters
 			ftyp := f.typ.(*Signature)
 			mtyp := m.typ.(*Signature)
 			if len(ftyp.tparams) != len(mtyp.tparams) {
 				return m, f
 			}
+			if len(ftyp.tparams) > 0 {
+				panic("internal error: method with type parameters")
+			}
 
 			// If the methods have type parameters we don't care whether they
 			// are the same or not, as long as they match up. Use unification
@@ -385,6 +389,9 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		if len(ftyp.tparams) != len(mtyp.tparams) {
 			return m, f
 		}
+		if len(ftyp.tparams) > 0 {
+			panic("internal error: method with type parameters")
+		}
 
 		// If V is a (instantiated) generic type, its methods are still
 		// parameterized using the original (declaration) receiver type
@@ -412,7 +419,7 @@ func (check *Checker) missingMethod(V Type, T *Interface, static bool) (method,
 		// TODO(gri) is this always correct? what about type bounds?
 		// (Alternative is to rename/subst type parameters and compare.)
 		u := newUnifier(check, true)
-		u.x.init(ftyp.tparams)
+		u.x.init(ftyp.rparams)
 		if !u.unify(ftyp, mtyp) {
 			return m, f
 		}
diff --git a/src/go/types/testdata/fixedbugs/issue46275.go2 b/src/go/types/testdata/fixedbugs/issue46275.go2
new file mode 100644
index 0000000000..0ebde31c8e
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue46275.go2
@@ -0,0 +1,27 @@
+// 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 issue46275
+
+type N[T any] struct {
+        *N[T]
+        t T
+}
+
+func (n *N[T]) Elem() T {
+        return n.t
+}
+
+type I interface {
+        Elem() string
+}
+
+func _() {
+        var n1 *N[string]
+        var _ I = n1
+        type NS N[string]
+        var n2 *NS
+        var _ I = n2
+}
+