diff --git a/src/cmd/compile/internal/types2/typestring.go b/src/cmd/compile/internal/types2/typestring.go
index da5de08758d..6083955306b 100644
--- a/src/cmd/compile/internal/types2/typestring.go
+++ b/src/cmd/compile/internal/types2/typestring.go
@@ -234,7 +234,7 @@ func (w *typeWriter) typ(typ Type) {
 		if t.targs != nil {
 			// instantiated type
 			w.typeList(t.targs.list())
-		} else if t.TParams().Len() != 0 {
+		} else if !w.hash && t.TParams().Len() != 0 { // For type hashing, don't need to format the TParams
 			// parameterized type
 			w.tParamList(t.TParams().list())
 		}
diff --git a/test/typeparam/issue48185a.dir/p.go b/test/typeparam/issue48185a.dir/p.go
new file mode 100644
index 00000000000..176c7f4de5c
--- /dev/null
+++ b/test/typeparam/issue48185a.dir/p.go
@@ -0,0 +1,19 @@
+// 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 p
+
+type MarshalOptions struct {
+	Marshalers *Marshalers
+}
+
+type Encoder struct {}
+
+type Marshalers = marshalers[MarshalOptions, Encoder]
+
+type marshalers[Options, Coder any] struct{}
+
+func MarshalFuncV1[T any](fn func(T) ([]byte, error)) *Marshalers {
+	return &Marshalers{}
+}
diff --git a/test/typeparam/issue48185a.dir/p_test.go b/test/typeparam/issue48185a.dir/p_test.go
new file mode 100644
index 00000000000..52c87a7e297
--- /dev/null
+++ b/test/typeparam/issue48185a.dir/p_test.go
@@ -0,0 +1,11 @@
+// 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 "p"
+
+func main() {
+	_ = p.MarshalFuncV1[int](func(int) ([]byte, error) { return nil, nil })
+}
diff --git a/test/typeparam/issue48185a.go b/test/typeparam/issue48185a.go
new file mode 100644
index 00000000000..40df49f83be
--- /dev/null
+++ b/test/typeparam/issue48185a.go
@@ -0,0 +1,7 @@
+// rundir
+
+// 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