diff --git a/helper/schema/resource_data.go b/helper/schema/resource_data.go
index 4f7a4b9931..26d607730e 100644
--- a/helper/schema/resource_data.go
+++ b/helper/schema/resource_data.go
@@ -52,6 +52,7 @@ const (
 type getResult struct {
 	Value          interface{}
 	ValueProcessed interface{}
+	Computed       bool
 	Exists         bool
 	Schema         *Schema
 }
@@ -221,7 +222,8 @@ func (d *ResourceData) init() {
 	d.newState = &copyState
 }
 
-func (d *ResourceData) diffChange(k string) (interface{}, interface{}, bool) {
+func (d *ResourceData) diffChange(
+	k string) (interface{}, interface{}, bool, bool) {
 	// Get the change between the state and the config.
 	o, n := d.getChange(k, getSourceState, getSourceConfig)
 	if !o.Exists {
@@ -232,7 +234,7 @@ func (d *ResourceData) diffChange(k string) (interface{}, interface{}, bool) {
 	}
 
 	// Return the old, new, and whether there is a change
-	return o.Value, n.Value, !reflect.DeepEqual(o.Value, n.Value)
+	return o.Value, n.Value, !reflect.DeepEqual(o.Value, n.Value), n.Computed
 }
 
 func (d *ResourceData) getChange(
@@ -516,17 +518,21 @@ func (d *ResourceData) getList(
 	}
 
 	// Get the entire list.
+	var result []interface{}
 	count := d.getList(k, []string{"#"}, schema, source)
-	result := make([]interface{}, count.Value.(int))
-	for i, _ := range result {
-		is := strconv.FormatInt(int64(i), 10)
-		result[i] = d.getList(k, []string{is}, schema, source).Value
+	if !count.Computed {
+		result = make([]interface{}, count.Value.(int))
+		for i, _ := range result {
+			is := strconv.FormatInt(int64(i), 10)
+			result[i] = d.getList(k, []string{is}, schema, source).Value
+		}
 	}
 
 	return getResult{
-		Value:  result,
-		Exists: count.Exists,
-		Schema: schema,
+		Value:    result,
+		Computed: count.Computed,
+		Exists:   count.Exists,
+		Schema:   schema,
 	}
 }
 
@@ -537,7 +543,7 @@ func (d *ResourceData) getPrimitive(
 	source getSource) getResult {
 	var result string
 	var resultProcessed interface{}
-	var resultSet bool
+	var resultComputed, resultSet bool
 	if d.state != nil && source >= getSourceState {
 		result, resultSet = d.state.Attributes[k]
 	}
@@ -555,6 +561,8 @@ func (d *ResourceData) getPrimitive(
 			resultSet = false
 		}
 
+		// If it is computed, set that.
+		resultComputed = d.config.IsComputed(k)
 	}
 
 	if d.diff != nil && source >= getSourceDiff {
@@ -615,6 +623,10 @@ func (d *ResourceData) getPrimitive(
 			break
 		}
 
+		if resultComputed {
+			break
+		}
+
 		v, err := strconv.ParseInt(result, 0, 0)
 		if err != nil {
 			panic(err)
@@ -628,6 +640,7 @@ func (d *ResourceData) getPrimitive(
 	return getResult{
 		Value:          resultValue,
 		ValueProcessed: resultProcessed,
+		Computed:       resultComputed,
 		Exists:         resultSet,
 		Schema:         schema,
 	}
diff --git a/helper/schema/schema.go b/helper/schema/schema.go
index 7d373bd0dc..cb3e11617d 100644
--- a/helper/schema/schema.go
+++ b/helper/schema/schema.go
@@ -434,7 +434,7 @@ func (m schemaMap) diffList(
 	schema *Schema,
 	diff *terraform.InstanceDiff,
 	d *ResourceData) error {
-	o, n, _ := d.diffChange(k)
+	o, n, _, computedList := d.diffChange(k)
 
 	// If we have an old value, but no new value set but we're computed,
 	// then nothing has changed.
@@ -460,6 +460,16 @@ func (m schemaMap) diffList(
 	// Get the counts
 	oldLen := len(os)
 	newLen := len(vs)
+	oldStr := strconv.FormatInt(int64(oldLen), 10)
+
+	// If the whole list is computed, then say that the # is computed
+	if computedList {
+		diff.Attributes[k+".#"] = &terraform.ResourceAttrDiff{
+			Old:         oldStr,
+			NewComputed: true,
+		}
+		return nil
+	}
 
 	// If the counts are not the same, then record that diff
 	changed := oldLen != newLen
@@ -471,11 +481,11 @@ func (m schemaMap) diffList(
 			ForceNew: schema.ForceNew,
 		}
 
-		oldStr := ""
 		newStr := ""
 		if !computed {
-			oldStr = strconv.FormatInt(int64(oldLen), 10)
 			newStr = strconv.FormatInt(int64(newLen), 10)
+		} else {
+			oldStr = ""
 		}
 
 		diff.Attributes[k+".#"] = countSchema.finalizeDiff(&terraform.ResourceAttrDiff{
@@ -534,7 +544,7 @@ func (m schemaMap) diffMap(
 
 	// First get all the values from the state
 	var stateMap, configMap map[string]string
-	o, n, _ := d.diffChange(k)
+	o, n, _, _ := d.diffChange(k)
 	if err := mapstructure.WeakDecode(o, &stateMap); err != nil {
 		return fmt.Errorf("%s: %s", k, err)
 	}
@@ -581,7 +591,7 @@ func (m schemaMap) diffString(
 	d *ResourceData) error {
 	var originalN interface{}
 	var os, ns string
-	o, n, _ := d.diffChange(k)
+	o, n, _, _ := d.diffChange(k)
 	if n == nil {
 		n = schema.Default
 		if schema.DefaultFunc != nil {
diff --git a/helper/schema/schema_test.go b/helper/schema/schema_test.go
index d3305a6859..23c283b380 100644
--- a/helper/schema/schema_test.go
+++ b/helper/schema/schema_test.go
@@ -428,6 +428,39 @@ func TestSchemaMap_Diff(t *testing.T) {
 			Err: false,
 		},
 
+		{
+			Schema: map[string]*Schema{
+				"ports": &Schema{
+					Type:     TypeList,
+					Required: true,
+					Elem:     &Schema{Type: TypeInt},
+				},
+			},
+
+			State: nil,
+
+			Config: map[string]interface{}{
+				"ports": []interface{}{1, "${var.foo}"},
+			},
+
+			ConfigVariables: map[string]string{
+				"var.foo": config.UnknownVariableValue +
+					config.InterpSplitDelim + "5",
+			},
+
+			Diff: &terraform.InstanceDiff{
+				Attributes: map[string]*terraform.ResourceAttrDiff{
+					"ports.#": &terraform.ResourceAttrDiff{
+						Old: "0",
+						New: "",
+						NewComputed: true,
+					},
+				},
+			},
+
+			Err: false,
+		},
+
 		{
 			Schema: map[string]*Schema{
 				"ports": &Schema{
diff --git a/terraform/resource.go b/terraform/resource.go
index b43d296acd..071c0592d4 100644
--- a/terraform/resource.go
+++ b/terraform/resource.go
@@ -128,6 +128,13 @@ func (c *ResourceConfig) Get(k string) (interface{}, bool) {
 	return c.get(k, c.Raw)
 }
 
+// IsComputed returns whether the given key is computed or not.
+func (c *ResourceConfig) IsComputed(k string) bool {
+	_, ok := c.get(k, c.Config)
+	_, okRaw := c.get(k, c.Raw)
+	return !ok && okRaw
+}
+
 // IsSet checks if the key in the configuration is set. A key is set if
 // it has a value or the value is being computed (is unknown currently).
 //