diff --git a/src/reflect/abi.go b/src/reflect/abi.go
index 50e6312172..002e4598b9 100644
--- a/src/reflect/abi.go
+++ b/src/reflect/abi.go
@@ -121,6 +121,7 @@ func (a *abiSeq) stepsForValue(i int) []abiStep {
 // If the value was stack-assigned, returns the single
 // abiStep describing that translation, and nil otherwise.
 func (a *abiSeq) addArg(t *rtype) *abiStep {
+	// We'll always be adding a new value, so do that first.
 	pStart := len(a.steps)
 	a.valueStart = append(a.valueStart, pStart)
 	if t.size == 0 {
@@ -141,8 +142,13 @@ func (a *abiSeq) addArg(t *rtype) *abiStep {
 		a.stackBytes = align(a.stackBytes, uintptr(t.align))
 		return nil
 	}
+	// Hold a copy of "a" so that we can roll back if
+	// register assignment fails.
+	aOld := *a
 	if !a.regAssign(t, 0) {
-		a.steps = a.steps[:pStart]
+		// Register assignment failed. Roll back any changes
+		// and stack-assign.
+		*a = aOld
 		a.stackAssign(t.size, uintptr(t.align))
 		return &a.steps[len(a.steps)-1]
 	}
diff --git a/src/reflect/abi_test.go b/src/reflect/abi_test.go
index 418896ee87..d658a0f6d3 100644
--- a/src/reflect/abi_test.go
+++ b/src/reflect/abi_test.go
@@ -85,6 +85,7 @@ func TestReflectValueCallABI(t *testing.T) {
 		passStruct13,
 		pass2Struct1,
 		passEmptyStruct,
+		passStruct10AndSmall,
 	} {
 		fn := reflect.ValueOf(fn)
 		t.Run(runtime.FuncForPC(fn.Pointer()).Name(), func(t *testing.T) {
@@ -339,6 +340,14 @@ func passEmptyStruct(a int, b struct{}, c float64) (int, struct{}, float64) {
 	return a, b, c
 }
 
+// This test case forces a large argument to the stack followed by more
+// in-register arguments.
+//go:registerparams
+//go:noinline
+func passStruct10AndSmall(a Struct10, b byte, c uint) (Struct10, byte, uint) {
+	return a, b, c
+}
+
 // Struct1 is a simple integer-only aggregate struct.
 type Struct1 struct {
 	A, B, C uint