diff --git a/src/cmd/compile/internal/ssa/stackalloc.go b/src/cmd/compile/internal/ssa/stackalloc.go
index ca7f95dee1..aadc6c4cfe 100644
--- a/src/cmd/compile/internal/ssa/stackalloc.go
+++ b/src/cmd/compile/internal/ssa/stackalloc.go
@@ -72,6 +72,7 @@ type stackValState struct {
 	typ      *types.Type
 	spill    *Value
 	needSlot bool
+	isArg    bool
 }
 
 // stackalloc allocates storage in the stack frame for
@@ -110,6 +111,7 @@ func (s *stackAllocState) init(f *Func, spillLive [][]ID) {
 		for _, v := range b.Values {
 			s.values[v.ID].typ = v.Type
 			s.values[v.ID].needSlot = !v.Type.IsMemory() && !v.Type.IsVoid() && !v.Type.IsFlags() && f.getHome(v.ID) == nil && !v.rematerializeable()
+			s.values[v.ID].isArg = v.Op == OpArg
 			if f.pass.debug > stackDebug && s.values[v.ID].needSlot {
 				fmt.Printf("%s needs a stack slot\n", v)
 			}
@@ -377,7 +379,9 @@ func (s *stackAllocState) buildInterferenceGraph() {
 			if s.values[v.ID].needSlot {
 				live.remove(v.ID)
 				for _, id := range live.contents() {
-					if s.values[v.ID].typ.Compare(s.values[id].typ) == types.CMPeq {
+					// Note: args can have different types and still interfere
+					// (with each other or with other values). See issue 23522.
+					if s.values[v.ID].typ.Compare(s.values[id].typ) == types.CMPeq || v.Op == OpArg || s.values[id].isArg {
 						s.interfere[v.ID] = append(s.interfere[v.ID], id)
 						s.interfere[id] = append(s.interfere[id], v.ID)
 					}
diff --git a/test/fixedbugs/issue23522.go b/test/fixedbugs/issue23522.go
new file mode 100644
index 0000000000..cace86c8ab
--- /dev/null
+++ b/test/fixedbugs/issue23522.go
@@ -0,0 +1,46 @@
+// run
+
+// Copyright 2018 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 (
+	"math"
+)
+
+type S struct {
+	u int64
+	n int32
+}
+
+func F1(f float64) *S {
+	s := f
+	pf := math.Copysign(f, 1)
+	u := math.Floor(pf)
+	return &S{
+		u: int64(math.Copysign(u, s)),
+		n: int32(math.Copysign((pf-u)*1e9, s)),
+	}
+}
+
+func F2(f float64) *S {
+	s := f
+	f = math.Copysign(f, 1)
+	u := math.Floor(f)
+	return &S{
+		u: int64(math.Copysign(u, s)),
+		n: int32(math.Copysign((f-u)*1e9, s)),
+	}
+}
+
+func main() {
+	s1 := F1(-1)
+	s2 := F2(-1)
+	if *s1 != *s2 {
+		println("F1:", s1.u, s1.n)
+		println("F2:", s2.u, s2.n)
+		panic("different")
+	}
+}