diff --git a/hclsyntax/expression.go b/hclsyntax/expression.go
index c1e2b28..41c8b77 100644
--- a/hclsyntax/expression.go
+++ b/hclsyntax/expression.go
@@ -788,6 +788,7 @@ func (e *ObjectConsExpr) walkChildNodes(w internalWalkFunc) {
 func (e *ObjectConsExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
 	var vals map[string]cty.Value
 	var diags hcl.Diagnostics
+	var marks []cty.ValueMarks
 
 	// This will get set to true if we fail to produce any of our keys,
 	// either because they are actually unknown or if the evaluation produces
@@ -825,18 +826,8 @@ func (e *ObjectConsExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics
 			continue
 		}
 
-		if key.IsMarked() {
-			diags = append(diags, &hcl.Diagnostic{
-				Severity:    hcl.DiagError,
-				Summary:     "Marked value as key",
-				Detail:      "Can't use a marked value as a key.",
-				Subject:     item.ValueExpr.Range().Ptr(),
-				Expression:  item.KeyExpr,
-				EvalContext: ctx,
-			})
-			known = false
-			continue
-		}
+		key, keyMarks := key.Unmark()
+		marks = append(marks, keyMarks)
 
 		var err error
 		key, err = convert.Convert(key, cty.String)
@@ -867,7 +858,7 @@ func (e *ObjectConsExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics
 		return cty.DynamicVal, diags
 	}
 
-	return cty.ObjectVal(vals), diags
+	return cty.ObjectVal(vals).WithMarks(marks...), diags
 }
 
 func (e *ObjectConsExpr) Range() hcl.Range {
@@ -997,6 +988,7 @@ type ForExpr struct {
 
 func (e *ForExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
 	var diags hcl.Diagnostics
+	var marks []cty.ValueMarks
 
 	collVal, collDiags := e.CollExpr.Value(ctx)
 	diags = append(diags, collDiags...)
@@ -1018,7 +1010,8 @@ func (e *ForExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
 	}
 	// Unmark collection before checking for iterability, because marked
 	// values cannot be iterated
-	collVal, marks := collVal.Unmark()
+	collVal, collMarks := collVal.Unmark()
+	marks = append(marks, collMarks)
 	if !collVal.CanIterateElements() {
 		diags = append(diags, &hcl.Diagnostic{
 			Severity: hcl.DiagError,
@@ -1198,18 +1191,8 @@ func (e *ForExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
 				continue
 			}
 
-			if key.IsMarked() {
-				diags = append(diags, &hcl.Diagnostic{
-					Severity:    hcl.DiagError,
-					Summary:     "Invalid object key",
-					Detail:      "Marked values cannot be used as object keys.",
-					Subject:     e.KeyExpr.Range().Ptr(),
-					Context:     &e.SrcRange,
-					Expression:  e.KeyExpr,
-					EvalContext: childCtx,
-				})
-				continue
-			}
+			key, keyMarks := key.Unmark()
+			marks = append(marks, keyMarks)
 
 			val, valDiags := e.ValExpr.Value(childCtx)
 			diags = append(diags, valDiags...)
@@ -1249,7 +1232,7 @@ func (e *ForExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
 			}
 		}
 
-		return cty.ObjectVal(vals).WithMarks(marks), diags
+		return cty.ObjectVal(vals).WithMarks(marks...), diags
 
 	} else {
 		// Producing a tuple
@@ -1335,7 +1318,7 @@ func (e *ForExpr) Value(ctx *hcl.EvalContext) (cty.Value, hcl.Diagnostics) {
 			return cty.DynamicVal, diags
 		}
 
-		return cty.TupleVal(vals).WithMarks(marks), diags
+		return cty.TupleVal(vals).WithMarks(marks...), diags
 	}
 }
 
diff --git a/hclsyntax/expression_test.go b/hclsyntax/expression_test.go
index 9129fbe..b420d93 100644
--- a/hclsyntax/expression_test.go
+++ b/hclsyntax/expression_test.go
@@ -516,8 +516,11 @@ upper(
 					}),
 				},
 			},
-			cty.DynamicVal,
-			1,
+			cty.ObjectVal(map[string]cty.Value{
+				"hello":   cty.StringVal("world"),
+				"goodbye": cty.StringVal("earth"),
+			}).Mark("marked"),
+			0,
 		},
 		{
 			`{"${var.greeting}" = "world"}`,
@@ -918,20 +921,44 @@ upper(
 			}),
 			0,
 		},
-		{ // Error when using marked value as object key
+		{
+			// Mark object if keys include marked values, members retain
+			// their original marks in their values
 			`{for v in things: v => "${v}-friend"}`,
 			&hcl.EvalContext{
 				Variables: map[string]cty.Value{
 					"things": cty.MapVal(map[string]cty.Value{
-						"a": cty.StringVal("rosie").Mark("sensitive"),
+						"a": cty.StringVal("rosie").Mark("marked"),
 						"b": cty.StringVal("robin"),
+						// Check for double-marking when a key val has a duplicate mark
+						"c": cty.StringVal("rowan").Mark("marked"),
+						"d": cty.StringVal("ruben").Mark("also-marked"),
 					}),
 				},
 			},
 			cty.ObjectVal(map[string]cty.Value{
+				"rosie": cty.StringVal("rosie-friend").Mark("marked"),
 				"robin": cty.StringVal("robin-friend"),
-			}),
-			1,
+				"rowan": cty.StringVal("rowan-friend").Mark("marked"),
+				"ruben": cty.StringVal("ruben-friend").Mark("also-marked"),
+			}).WithMarks(cty.NewValueMarks("marked", "also-marked")),
+			0,
+		},
+		{ // object itself is marked, contains marked value
+			`{for v in things: v => "${v}-friend"}`,
+			&hcl.EvalContext{
+				Variables: map[string]cty.Value{
+					"things": cty.MapVal(map[string]cty.Value{
+						"a": cty.StringVal("rosie").Mark("marked"),
+						"b": cty.StringVal("robin"),
+					}).Mark("marks"),
+				},
+			},
+			cty.ObjectVal(map[string]cty.Value{
+				"rosie": cty.StringVal("rosie-friend").Mark("marked"),
+				"robin": cty.StringVal("robin-friend"),
+			}).WithMarks(cty.NewValueMarks("marked", "marks")),
+			0,
 		},
 		{ // Sequence for loop with marked conditional expression
 			`[for x in things: x if x != secret]`,