diff --git a/test/run.go b/test/run.go
index ff3cc1aabb..c8e8ab9dfc 100644
--- a/test/run.go
+++ b/test/run.go
@@ -1964,8 +1964,10 @@ var types2Failures32Bit = setOf(
 )
 
 var go118Failures = setOf(
-	"typeparam/nested.go",     // 1.18 compiler doesn't support function-local types with generics
-	"typeparam/issue51521.go", // 1.18 compiler produces bad panic message and link error
+	"typeparam/nested.go",      // 1.18 compiler doesn't support function-local types with generics
+	"typeparam/issue51521.go",  // 1.18 compiler produces bad panic message and link error
+	"typeparam/mdempsky/16.go", // 1.18 compiler uses interface shape type in failed type assertions
+	"typeparam/mdempsky/17.go", // 1.18 compiler mishandles implicit conversions from range loops
 )
 
 // In all of these cases, the 1.17 compiler reports reasonable errors, but either the
diff --git a/test/typeparam/mdempsky/16.go b/test/typeparam/mdempsky/16.go
new file mode 100644
index 0000000000..f4f79b9aac
--- /dev/null
+++ b/test/typeparam/mdempsky/16.go
@@ -0,0 +1,34 @@
+// run
+
+// Copyright 2022 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.
+
+// Test that type assertion panics mention the real interface type,
+// not their shape type.
+
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+)
+
+func main() {
+	// The exact error message isn't important, but it should mention
+	// `main.T`, not `go.shape.int_0`.
+	if have := F[T](); !strings.Contains(have, "interface { T() main.T }") {
+		fmt.Printf("FAIL: unexpected panic message: %q\n", have)
+	}
+}
+
+type T int
+
+func F[T any]() (res string) {
+	defer func() {
+		res = recover().(runtime.Error).Error()
+	}()
+	_ = interface{ T() T }(nil).(T)
+	return
+}
diff --git a/test/typeparam/mdempsky/17.go b/test/typeparam/mdempsky/17.go
new file mode 100644
index 0000000000..12385c3f9e
--- /dev/null
+++ b/test/typeparam/mdempsky/17.go
@@ -0,0 +1,110 @@
+// run
+
+// Copyright 2022 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.
+
+// Test that implicit conversions of derived types to interface type
+// in range loops work correctly.
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+)
+
+func main() {
+	test{"int", "V"}.match(RangeArrayAny[V]())
+	test{"int", "V"}.match(RangeArrayIface[V]())
+	test{"V"}.match(RangeChanAny[V]())
+	test{"V"}.match(RangeChanIface[V]())
+	test{"K", "V"}.match(RangeMapAny[K, V]())
+	test{"K", "V"}.match(RangeMapIface[K, V]())
+	test{"int", "V"}.match(RangeSliceAny[V]())
+	test{"int", "V"}.match(RangeSliceIface[V]())
+}
+
+type test []string
+
+func (t test) match(args ...any) {
+	if len(t) != len(args) {
+		fmt.Printf("FAIL: want %v values, have %v\n", len(t), len(args))
+		return
+	}
+	for i, want := range t {
+		if have := reflect.TypeOf(args[i]).Name(); want != have {
+			fmt.Printf("FAIL: %v: want type %v, have %v\n", i, want, have)
+		}
+	}
+}
+
+type iface interface{ M() int }
+
+type K int
+type V int
+
+func (K) M() int { return 0 }
+func (V) M() int { return 0 }
+
+func RangeArrayAny[V any]() (k, v any) {
+	for k, v = range [...]V{zero[V]()} {
+	}
+	return
+}
+
+func RangeArrayIface[V iface]() (k any, v iface) {
+	for k, v = range [...]V{zero[V]()} {
+	}
+	return
+}
+
+func RangeChanAny[V any]() (v any) {
+	for v = range chanOf(zero[V]()) {
+	}
+	return
+}
+
+func RangeChanIface[V iface]() (v iface) {
+	for v = range chanOf(zero[V]()) {
+	}
+	return
+}
+
+func RangeMapAny[K comparable, V any]() (k, v any) {
+	for k, v = range map[K]V{zero[K](): zero[V]()} {
+	}
+	return
+}
+
+func RangeMapIface[K interface {
+	iface
+	comparable
+}, V iface]() (k, v iface) {
+	for k, v = range map[K]V{zero[K](): zero[V]()} {
+	}
+	return
+}
+
+func RangeSliceAny[V any]() (k, v any) {
+	for k, v = range []V{zero[V]()} {
+	}
+	return
+}
+
+func RangeSliceIface[V iface]() (k any, v iface) {
+	for k, v = range []V{zero[V]()} {
+	}
+	return
+}
+
+func chanOf[T any](elems ...T) chan T {
+	c := make(chan T, len(elems))
+	for _, elem := range elems {
+		c <- elem
+	}
+	close(c)
+	return c
+}
+
+func zero[T any]() (_ T) { return }