diff --git a/lang/types/type.go b/lang/types/type.go
index 4bc4893e..b473f18f 100644
--- a/lang/types/type.go
+++ b/lang/types/type.go
@@ -553,8 +553,11 @@ func (obj *Type) String() string {
 			if t == nil {
 				panic("malformed func field")
 			}
-			//s[i] = fmt.Sprintf("%s %s", k, t.String()) // strict
-			s[i] = t.String()
+
+			// We need to print function arg names for Copy() to use
+			// the String() hack here and avoid erasing them here!
+			//s[i] = t.String()
+			s[i] = fmt.Sprintf("%s %s", k, t.String()) // strict
 		}
 		var out string
 		if obj.Out != nil {
@@ -723,6 +726,7 @@ func (obj *Type) Cmp(typ *Type) error {
 
 // Copy copies this type so that inplace modification won't affect the original.
 func (obj *Type) Copy() *Type {
+	// String() needs to print function arg names or they'd get erased here!
 	return NewType(obj.String()) // hack to do this easily
 }
 
diff --git a/lang/types/type_test.go b/lang/types/type_test.go
index 3e92eeaf..4ffc9d76 100644
--- a/lang/types/type_test.go
+++ b/lang/types/type_test.go
@@ -501,7 +501,7 @@ func TestType1(t *testing.T) {
 				Kind: KindFloat,
 			},
 		},
-		"func(str) bool": {
+		"func(a0 str) bool": {
 			Kind: KindFunc,
 			// key names are arbitrary...
 			Map: map[string]*Type{
@@ -516,7 +516,7 @@ func TestType1(t *testing.T) {
 				Kind: KindBool,
 			},
 		},
-		"func(str, int) bool": {
+		"func(hello str, answer int) bool": {
 			Kind: KindFunc,
 			// key names are arbitrary...
 			Map: map[string]*Type{
@@ -535,7 +535,7 @@ func TestType1(t *testing.T) {
 				Kind: KindBool,
 			},
 		},
-		"func(str, []int, float) bool": {
+		"func(a0 str, a1 []int, a2 float) bool": {
 			Kind: KindFunc,
 			// key names are arbitrary...
 			Map: map[string]*Type{
@@ -561,7 +561,7 @@ func TestType1(t *testing.T) {
 				Kind: KindBool,
 			},
 		},
-		"func(map{str: int}) bool": {
+		"func(answer map{str: int}) bool": {
 			Kind: KindFunc,
 			// key names are arbitrary...
 			Map: map[string]*Type{
@@ -582,7 +582,7 @@ func TestType1(t *testing.T) {
 				Kind: KindBool,
 			},
 		},
-		"func(bool, map{str: int}) bool": {
+		"func(hello bool, answer map{str: int}) bool": {
 			Kind: KindFunc,
 			// key names are arbitrary...
 			Map: map[string]*Type{
@@ -607,7 +607,7 @@ func TestType1(t *testing.T) {
 				Kind: KindBool,
 			},
 		},
-		"func(struct{a str; bb int}) bool": {
+		"func(answer struct{a str; bb int}) bool": {
 			Kind: KindFunc,
 			// key names are arbitrary...
 			Map: map[string]*Type{
@@ -634,7 +634,7 @@ func TestType1(t *testing.T) {
 				Kind: KindBool,
 			},
 		},
-		"func(bool, struct{a str; bb int}) bool": {
+		"func(hello bool, answer struct{a str; bb int}) bool": {
 			Kind: KindFunc,
 			// key names are arbitrary...
 			Map: map[string]*Type{
@@ -1472,6 +1472,20 @@ func TestComplexCmp0(t *testing.T) {
 	}
 }
 
+func TestTypeCopy0(t *testing.T) {
+	typ := NewType("func(arg0 str, arg1 bool) int")
+	cp := typ.Copy()
+	if len(cp.Ord) != 2 {
+		t.Errorf("incorrect ord length after Copy")
+	}
+	if cp.Ord[0] != "arg0" {
+		t.Errorf("incorrect 0th arg name after Copy")
+	}
+	if cp.Ord[1] != "arg1" {
+		t.Errorf("incorrect 1st arg name after Copy")
+	}
+}
+
 func TestTypeOf0(t *testing.T) {
 	// TODO: implement testing of the TypeOf function
 	// TODO: implement testing TypeOf for struct field name mappings