diff --git a/zcl/zclsyntax/expression.go b/zcl/zclsyntax/expression.go
index 65a038b..bad6fbe 100644
--- a/zcl/zclsyntax/expression.go
+++ b/zcl/zclsyntax/expression.go
@@ -697,7 +697,13 @@ func (e *ForExpr) Value(ctx *zcl.EvalContext) (cty.Value, zcl.Diagnostics) {
 
 	if e.KeyExpr != nil {
 		// Producing an object
-		vals := map[string]cty.Value{}
+		var vals map[string]cty.Value
+		var groupVals map[string][]cty.Value
+		if e.Group {
+			groupVals = map[string][]cty.Value{}
+		} else {
+			vals = map[string]cty.Value{}
+		}
 
 		it := collVal.ElementIterator()
 
@@ -791,13 +797,26 @@ func (e *ForExpr) Value(ctx *zcl.EvalContext) (cty.Value, zcl.Diagnostics) {
 
 			val, valDiags := e.ValExpr.Value(childCtx)
 			diags = append(diags, valDiags...)
-			vals[key.AsString()] = val
+
+			if e.Group {
+				k := key.AsString()
+				groupVals[k] = append(groupVals[k], val)
+			} else {
+				vals[key.AsString()] = val
+			}
 		}
 
 		if !known {
 			return cty.DynamicVal, diags
 		}
 
+		if e.Group {
+			vals = map[string]cty.Value{}
+			for k, gvs := range groupVals {
+				vals[k] = cty.TupleVal(gvs)
+			}
+		}
+
 		return cty.ObjectVal(vals), diags
 
 	} else {
diff --git a/zcl/zclsyntax/expression_test.go b/zcl/zclsyntax/expression_test.go
index b3b59cb..73a4149 100644
--- a/zcl/zclsyntax/expression_test.go
+++ b/zcl/zclsyntax/expression_test.go
@@ -509,6 +509,26 @@ upper(
 			}),
 			1, // must have a key expr when producing a map
 		},
+		{
+			`{for i, v in ["a", "b", "c", "b", "d"]: v => i...}`,
+			nil,
+			cty.ObjectVal(map[string]cty.Value{
+				"a": cty.TupleVal([]cty.Value{
+					cty.NumberIntVal(0),
+				}),
+				"b": cty.TupleVal([]cty.Value{
+					cty.NumberIntVal(1),
+					cty.NumberIntVal(3),
+				}),
+				"c": cty.TupleVal([]cty.Value{
+					cty.NumberIntVal(2),
+				}),
+				"d": cty.TupleVal([]cty.Value{
+					cty.NumberIntVal(4),
+				}),
+			}),
+			0,
+		},
 		{
 			`[for v in {hello: "world"}: v...]`,
 			nil,