diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 1acc8c7fb6..5f770166db 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -777,8 +777,13 @@ func (dict *readerDict) mangle(sym *types.Sym) *types.Sym {
 		return sym
 	}
 
+	// If sym is a locally defined generic type, we need the suffix to
+	// stay at the end after mangling so that types/fmt.go can strip it
+	// out again when writing the type's runtime descriptor (#54456).
+	base, suffix := types.SplitVargenSuffix(sym.Name)
+
 	var buf strings.Builder
-	buf.WriteString(sym.Name)
+	buf.WriteString(base)
 	buf.WriteByte('[')
 	for i, targ := range dict.targs {
 		if i > 0 {
@@ -791,6 +796,7 @@ func (dict *readerDict) mangle(sym *types.Sym) *types.Sym {
 		buf.WriteString(targ.LinkString())
 	}
 	buf.WriteByte(']')
+	buf.WriteString(suffix)
 	return sym.Pkg.Lookup(buf.String())
 }
 
diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
index d9cd1cbd32..c2c3567220 100644
--- a/src/cmd/compile/internal/noder/writer.go
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -933,8 +933,11 @@ func (w *writer) qualifiedIdent(obj types2.Object) {
 		decl, ok := w.p.typDecls[obj.(*types2.TypeName)]
 		assert(ok)
 		if decl.gen != 0 {
-			// TODO(mdempsky): Find a better solution than embedding middle
-			// dot in the symbol name; this is terrible.
+			// For local defined types, we embed a scope-disambiguation
+			// number directly into their name. types.SplitVargenSuffix then
+			// knows to look for this.
+			//
+			// TODO(mdempsky): Find a better solution; this is terrible.
 			name = fmt.Sprintf("%s·%v", name, decl.gen)
 		}
 	}
diff --git a/src/cmd/compile/internal/types/fmt.go b/src/cmd/compile/internal/types/fmt.go
index c1138643b7..c6e99d26c2 100644
--- a/src/cmd/compile/internal/types/fmt.go
+++ b/src/cmd/compile/internal/types/fmt.go
@@ -340,13 +340,9 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 		// non-fmtTypeID modes.
 		sym := t.Sym()
 		if mode != fmtTypeID {
-			i := len(sym.Name)
-			for i > 0 && sym.Name[i-1] >= '0' && sym.Name[i-1] <= '9' {
-				i--
-			}
-			const dot = "·"
-			if i >= len(dot) && sym.Name[i-len(dot):i] == dot {
-				sym = &Sym{Pkg: sym.Pkg, Name: sym.Name[:i-len(dot)]}
+			base, _ := SplitVargenSuffix(sym.Name)
+			if len(base) < len(sym.Name) {
+				sym = &Sym{Pkg: sym.Pkg, Name: base}
 			}
 		}
 		sconv2(b, sym, verb, mode)
@@ -704,6 +700,21 @@ func fldconv(b *bytes.Buffer, f *Field, verb rune, mode fmtMode, visited map[*Ty
 	}
 }
 
+// SplitVargenSuffix returns name split into a base string and a ·N
+// suffix, if any.
+func SplitVargenSuffix(name string) (base, suffix string) {
+	i := len(name)
+	for i > 0 && name[i-1] >= '0' && name[i-1] <= '9' {
+		i--
+	}
+	const dot = "·"
+	if i >= len(dot) && name[i-len(dot):i] == dot {
+		i -= len(dot)
+		return name[:i], name[i:]
+	}
+	return name, ""
+}
+
 // Val
 
 func FmtConst(v constant.Value, sharp bool) string {
diff --git a/test/run.go b/test/run.go
index 21f0f7d634..58d09b6b59 100644
--- a/test/run.go
+++ b/test/run.go
@@ -1990,6 +1990,7 @@ var go118Failures = setOf(
 	"fixedbugs/issue54343.go",  // 1.18 compiler assigns receiver parameter to global variable
 	"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/issue54456.go",  // 1.18 compiler fails to distinguish local generic types
 	"typeparam/issue54497.go",  // 1.18 compiler is more conservative about inlining due to repeated issues
 	"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
diff --git a/test/typeparam/issue54456.go b/test/typeparam/issue54456.go
new file mode 100644
index 0000000000..8342163e51
--- /dev/null
+++ b/test/typeparam/issue54456.go
@@ -0,0 +1,37 @@
+// 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.
+
+// The Go 1.18 frontend failed to disambiguate instantiations of
+// different, locally defined generic types with the same name.
+//
+// The unified frontend also exposed the scope-disambiguation mangling
+// to end users in reflect data.
+
+package main
+
+import (
+	"reflect"
+)
+
+func one() any { type T[_ any] int; return T[int](0) }
+func two() any { type T[_ any] int; return T[int](0) }
+
+func main() {
+	p, q := one(), two()
+
+	// p and q have different dynamic types; this comparison should
+	// evaluate false.
+	if p == q {
+		panic("bad type identity")
+	}
+
+	for _, x := range []any{p, q} {
+		// The names here should not contain "·1" or "·2".
+		if name := reflect.TypeOf(x).String(); name != "main.T[int]" {
+			panic(name)
+		}
+	}
+}
diff --git a/test/typeparam/nested.out b/test/typeparam/nested.out
index 37cb762e32..0836d9b0dc 100644
--- a/test/typeparam/nested.out
+++ b/test/typeparam/nested.out
@@ -1,4 +1,4 @@
-0,3: main.T·2[int;int]
-4,7: main.T·2[int;main.U·3[int;int]]
-22,23: main.T·2[main.Int;main.Int]
-26,27: main.T·2[main.Int;main.U·3[main.Int;main.Int]]
+0,3: main.T[int;int]
+4,7: main.T[int;main.U[int;int]·3]
+22,23: main.T[main.Int;main.Int]
+26,27: main.T[main.Int;main.U[main.Int;main.Int]·3]