diff --git a/lang/funcs/collection.go b/lang/funcs/collection.go
index 38d7269cec..63a08e5ec6 100644
--- a/lang/funcs/collection.go
+++ b/lang/funcs/collection.go
@@ -264,10 +264,6 @@ var DistinctFunc = function.New(&function.Spec{
 	},
 	Type: function.StaticReturnType(cty.List(cty.DynamicPseudoType)),
 	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
-		if len(args) != 1 {
-			return cty.NilVal, fmt.Errorf("distinct accepts only one argument")
-		}
-
 		var list []cty.Value
 
 		for it := args[0].ElementIterator(); it.Next(); {
@@ -295,7 +291,9 @@ var ChunklistFunc = function.New(&function.Spec{
 			Type: cty.Number,
 		},
 	},
-	Type: function.StaticReturnType(cty.List(cty.DynamicPseudoType)),
+	Type: func(args []cty.Value) (cty.Type, error) {
+		return cty.List(args[0].Type()), nil
+	},
 	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
 		var size int
 		err = gocty.FromCtyValue(args[1], &size)
diff --git a/lang/funcs/collection_test.go b/lang/funcs/collection_test.go
index 5796f1e5f0..dbab50d351 100644
--- a/lang/funcs/collection_test.go
+++ b/lang/funcs/collection_test.go
@@ -459,6 +459,17 @@ func TestContains(t *testing.T) {
 			cty.BoolVal(false),
 			false,
 		},
+		{ // Check a list with an unknown value
+			cty.ListVal([]cty.Value{
+				cty.UnknownVal(cty.String),
+				cty.StringVal("quick"),
+				cty.StringVal("brown"),
+				cty.StringVal("fox"),
+			}),
+			cty.StringVal("quick"),
+			cty.BoolVal(true),
+			false,
+		},
 	}
 
 	for _, test := range tests {
@@ -474,7 +485,7 @@ func TestContains(t *testing.T) {
 				t.Fatalf("unexpected error: %s", err)
 			}
 
-			if got != test.Want {
+			if !got.RawEquals(test.Want) {
 				t.Errorf("wrong result\ngot:  %#v\nwant: %#v", got, test.Want)
 			}
 		})