diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 0885007..df49d74 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -1822,9 +1822,25 @@
 	instSym := baseSym.Pkg.Lookup(name)
 	if instSym.Def != nil {
 		// May match existing type from previous import or
-		// types2-to-types1 conversion, or from in-progress instantiation
-		// in the current type import stack.
-		return instSym.Def.Type()
+		// types2-to-types1 conversion.
+		t := instSym.Def.Type()
+		if t.Kind() != types.TFORW {
+			return t
+		}
+		// Or, we have started creating this type in (*TSubster).Typ, but its
+		// underlying type was not completed yet, so we need to add this type
+		// to deferredInstStack, if not already there.
+		found := false
+		for _, t2 := range deferredInstStack {
+			if t2 == t {
+				found = true
+				break
+			}
+		}
+		if !found {
+			deferredInstStack = append(deferredInstStack, t)
+		}
+		return t
 	}
 
 	t := NewIncompleteNamedType(baseType.Pos(), instSym)
@@ -1865,6 +1881,7 @@
 // during a type substitution for an instantiation. This is needed for
 // instantiations of mutually recursive types.
 func doInst(t *types.Type) *types.Type {
+	assert(t.Kind() == types.TFORW)
 	return Instantiate(t.Pos(), t.OrigSym().Def.(*ir.Name).Type(), t.RParams())
 }
 
@@ -1873,6 +1890,7 @@
 // instantiation being created, baseType is the base generic type, and targs are
 // the type arguments that baseType is being instantiated with.
 func substInstType(t *types.Type, baseType *types.Type, targs []*types.Type) {
+	assert(t.Kind() == types.TFORW)
 	subst := Tsubster{
 		Tparams:       baseType.RParams(),
 		Targs:         targs,
diff --git a/src/cmd/compile/internal/typecheck/subr.go b/src/cmd/compile/internal/typecheck/subr.go
index 6824032..6288d15 100644
--- a/src/cmd/compile/internal/typecheck/subr.go
+++ b/src/cmd/compile/internal/typecheck/subr.go
@@ -1217,7 +1217,7 @@
 		}
 	case types.TFORW:
 		if ts.SubstForwFunc != nil {
-			newt = ts.SubstForwFunc(t)
+			return ts.SubstForwFunc(forw)
 		} else {
 			assert(false)
 		}
diff --git a/test/typeparam/issue48716.dir/a.go b/test/typeparam/issue48716.dir/a.go
new file mode 100644
index 0000000..63e599d
--- /dev/null
+++ b/test/typeparam/issue48716.dir/a.go
@@ -0,0 +1,51 @@
+// 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 a
+
+type Pair[L, R any] struct {
+	L L
+	R R
+}
+
+func Two[L, R any](l L, r R) Pair[L, R] {
+	return Pair[L, R]{L: l, R: r}
+}
+
+type Map[K, V any] interface {
+	Put(K, V)
+	Len() int
+	Iterate(func(Pair[K, V]) bool)
+}
+
+type HashMap[K comparable, V any] struct {
+	m map[K]V
+}
+
+func NewHashMap[K comparable, V any](capacity int) HashMap[K, V] {
+	var m map[K]V
+	if capacity >= 1 {
+		m = make(map[K]V, capacity)
+	} else {
+		m = map[K]V{}
+	}
+
+	return HashMap[K, V]{m: m}
+}
+
+func (m HashMap[K, V]) Put(k K, v V) {
+	m.m[k] = v
+}
+
+func (m HashMap[K, V]) Len() int {
+	return len(m.m)
+}
+
+func (m HashMap[K, V]) Iterate(cb func(Pair[K, V]) bool) {
+	for k, v := range m.m {
+		if !cb(Two(k, v)) {
+			return
+		}
+	}
+}
diff --git a/test/typeparam/issue48716.dir/main.go b/test/typeparam/issue48716.dir/main.go
new file mode 100644
index 0000000..adde0f5
--- /dev/null
+++ b/test/typeparam/issue48716.dir/main.go
@@ -0,0 +1,58 @@
+// 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
+
+import (
+	"a"
+)
+
+// Creates copy of set
+func Copy[T comparable](src MapSet[T]) (dst MapSet[T]) {
+	dst = HashSet[T](src.Len())
+	Fill(src, dst)
+	return
+}
+
+// Fill src from dst
+func Fill[T any](src, dst MapSet[T]) {
+	src.Iterate(func(t T) bool {
+		dst.Add(t)
+		return true
+	})
+	return
+}
+
+type MapSet[T any] struct {
+	m a.Map[T, struct{}]
+}
+
+func HashSet[T comparable](capacity int) MapSet[T] {
+	return FromMap[T](a.NewHashMap[T, struct{}](capacity))
+}
+
+func FromMap[T any](m a.Map[T, struct{}]) MapSet[T] {
+	return MapSet[T]{
+		m: m,
+	}
+}
+
+func (s MapSet[T]) Add(t T) {
+	s.m.Put(t, struct{}{})
+}
+
+func (s MapSet[T]) Len() int {
+	return s.m.Len()
+}
+
+func (s MapSet[T]) Iterate(cb func(T) bool) {
+	s.m.Iterate(func(p a.Pair[T, struct{}]) bool {
+		return cb(p.L)
+	})
+}
+
+func main() {
+	x := FromMap[int](a.NewHashMap[int, struct{}](1))
+	Copy[int](x)
+}
diff --git a/test/typeparam/issue48716.go b/test/typeparam/issue48716.go
new file mode 100644
index 0000000..76930e5
--- /dev/null
+++ b/test/typeparam/issue48716.go
@@ -0,0 +1,7 @@
+// rundir -G=3
+
+// 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 ignored