diff --git a/src/cmd/compile/internal/types2/expr.go b/src/cmd/compile/internal/types2/expr.go
index 33d329f82d8..b11cd1e9d8d 100644
--- a/src/cmd/compile/internal/types2/expr.go
+++ b/src/cmd/compile/internal/types2/expr.go
@@ -1741,16 +1741,33 @@ Error:
 	return statement // avoid follow-up errors
 }
 
+// keyVal maps a complex, float, integer, string or boolean constant value
+// to the corresponding complex128, float64, int64, uint64, string, or bool
+// Go value if possible; otherwise it returns x.
+// A complex constant that can be represented as a float (such as 1.2 + 0i)
+// is returned as a floating point value; if a floating point value can be
+// represented as an integer (such as 1.0) it is returned as an integer value.
+// This ensures that constants of different kind but equal value (such as
+// 1.0 + 0i, 1.0, 1) result in the same value.
 func keyVal(x constant.Value) interface{} {
-	// TODO(gri) This function must map 1, 1.0, and 1.0 + 0i to the same (integer) value.
-	//           Same for 1.1 and 1.1 + 0i.
-	//           Otherwise we won't get duplicate key errors for certain type parameter
-	//           key types. See issue #51610.
 	switch x.Kind() {
-	case constant.Bool:
-		return constant.BoolVal(x)
-	case constant.String:
-		return constant.StringVal(x)
+	case constant.Complex:
+		f := constant.ToFloat(x)
+		if f.Kind() != constant.Float {
+			r, _ := constant.Float64Val(constant.Real(x))
+			i, _ := constant.Float64Val(constant.Imag(x))
+			return complex(r, i)
+		}
+		x = f
+		fallthrough
+	case constant.Float:
+		i := constant.ToInt(x)
+		if i.Kind() != constant.Int {
+			v, _ := constant.Float64Val(x)
+			return v
+		}
+		x = i
+		fallthrough
 	case constant.Int:
 		if v, ok := constant.Int64Val(x); ok {
 			return v
@@ -1758,13 +1775,10 @@ func keyVal(x constant.Value) interface{} {
 		if v, ok := constant.Uint64Val(x); ok {
 			return v
 		}
-	case constant.Float:
-		v, _ := constant.Float64Val(x)
-		return v
-	case constant.Complex:
-		r, _ := constant.Float64Val(constant.Real(x))
-		i, _ := constant.Float64Val(constant.Imag(x))
-		return complex(r, i)
+	case constant.String:
+		return constant.StringVal(x)
+	case constant.Bool:
+		return constant.BoolVal(x)
 	}
 	return x
 }
diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51610.go b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51610.go
new file mode 100644
index 00000000000..d10c7885035
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue51610.go
@@ -0,0 +1,9 @@
+// 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.
+
+package p
+
+func _[P int | float64 | complex128]() {
+	_ = map[P]int{1: 1, 1.0 /* ERROR duplicate key 1 */ : 2, 1 /* ERROR duplicate key \(1 \+ 0i\) */ + 0i: 3}
+}
diff --git a/src/go/types/expr.go b/src/go/types/expr.go
index 14ca0c20d80..0e8dca32478 100644
--- a/src/go/types/expr.go
+++ b/src/go/types/expr.go
@@ -1663,16 +1663,33 @@ Error:
 	return statement // avoid follow-up errors
 }
 
-func keyVal(x constant.Value) any {
-	// TODO(gri) This function must map 1, 1.0, and 1.0 + 0i to the same (integer) value.
-	//           Same for 1.1 and 1.1 + 0i.
-	//           Otherwise we won't get duplicate key errors for certain type parameter
-	//           key types. See issue #51610.
+// keyVal maps a complex, float, integer, string or boolean constant value
+// to the corresponding complex128, float64, int64, uint64, string, or bool
+// Go value if possible; otherwise it returns x.
+// A complex constant that can be represented as a float (such as 1.2 + 0i)
+// is returned as a floating point value; if a floating point value can be
+// represented as an integer (such as 1.0) it is returned as an integer value.
+// This ensures that constants of different kind but equal value (such as
+// 1.0 + 0i, 1.0, 1) result in the same value.
+func keyVal(x constant.Value) interface{} {
 	switch x.Kind() {
-	case constant.Bool:
-		return constant.BoolVal(x)
-	case constant.String:
-		return constant.StringVal(x)
+	case constant.Complex:
+		f := constant.ToFloat(x)
+		if f.Kind() != constant.Float {
+			r, _ := constant.Float64Val(constant.Real(x))
+			i, _ := constant.Float64Val(constant.Imag(x))
+			return complex(r, i)
+		}
+		x = f
+		fallthrough
+	case constant.Float:
+		i := constant.ToInt(x)
+		if i.Kind() != constant.Int {
+			v, _ := constant.Float64Val(x)
+			return v
+		}
+		x = i
+		fallthrough
 	case constant.Int:
 		if v, ok := constant.Int64Val(x); ok {
 			return v
@@ -1680,13 +1697,10 @@ func keyVal(x constant.Value) any {
 		if v, ok := constant.Uint64Val(x); ok {
 			return v
 		}
-	case constant.Float:
-		v, _ := constant.Float64Val(x)
-		return v
-	case constant.Complex:
-		r, _ := constant.Float64Val(constant.Real(x))
-		i, _ := constant.Float64Val(constant.Imag(x))
-		return complex(r, i)
+	case constant.String:
+		return constant.StringVal(x)
+	case constant.Bool:
+		return constant.BoolVal(x)
 	}
 	return x
 }
diff --git a/src/go/types/testdata/fixedbugs/issue51610.go b/src/go/types/testdata/fixedbugs/issue51610.go
new file mode 100644
index 00000000000..d10c7885035
--- /dev/null
+++ b/src/go/types/testdata/fixedbugs/issue51610.go
@@ -0,0 +1,9 @@
+// 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.
+
+package p
+
+func _[P int | float64 | complex128]() {
+	_ = map[P]int{1: 1, 1.0 /* ERROR duplicate key 1 */ : 2, 1 /* ERROR duplicate key \(1 \+ 0i\) */ + 0i: 3}
+}