diff --git a/plans/changes.go b/plans/changes.go
index 4f7c6f676..bb4ca43bd 100644
--- a/plans/changes.go
+++ b/plans/changes.go
@@ -55,6 +55,15 @@ func (c *Changes) ResourceInstanceDeposed(addr addrs.AbsResourceInstance, key st
 	return nil
 }
 
+// SyncWrapper returns a wrapper object around the receiver that can be used
+// to make certain changes to the receiver in a concurrency-safe way, as long
+// as all callers share the same wrapper object.
+func (c *Changes) SyncWrapper() *ChangesSync {
+	return &ChangesSync{
+		changes: c,
+	}
+}
+
 // ResourceInstanceChange describes a change to a particular resource instance
 // object.
 type ResourceInstanceChange struct {
diff --git a/plans/changes_src.go b/plans/changes_src.go
index f97e5fbd4..7d195d2ae 100644
--- a/plans/changes_src.go
+++ b/plans/changes_src.go
@@ -66,6 +66,38 @@ func (rcs *ResourceInstanceChangeSrc) Decode(ty cty.Type) (*ResourceInstanceChan
 	}, nil
 }
 
+// DeepCopy creates a copy of the receiver where any pointers to nested mutable
+// values are also copied, thus ensuring that future mutations of the receiver
+// will not affect the copy.
+//
+// Some types used within a resource change are immutable by convention even
+// though the Go language allows them to be mutated, such as the types from
+// the addrs package. These are _not_ copied by this method, under the
+// assumption that callers will behave themselves.
+func (rcs *ResourceInstanceChangeSrc) DeepCopy() *ResourceInstanceChangeSrc {
+	if rcs == nil {
+		return nil
+	}
+	ret := *rcs
+
+	if len(ret.RequiredReplace) != 0 {
+		rr := make([]cty.Path, len(ret.RequiredReplace))
+		copy(rr, ret.RequiredReplace)
+		ret.RequiredReplace = rr
+	}
+
+	if len(ret.Private) != 0 {
+		private := make([]byte, len(ret.Private))
+		copy(private, ret.Private)
+		ret.Private = private
+	}
+
+	ret.ChangeSrc.Before = ret.ChangeSrc.Before.Copy()
+	ret.ChangeSrc.After = ret.ChangeSrc.After.Copy()
+
+	return &ret
+}
+
 // OutputChange describes a change to an output value.
 type OutputChangeSrc struct {
 	// ChangeSrc is an embedded description of the not-yet-decoded change.
diff --git a/plans/changes_sync.go b/plans/changes_sync.go
index eec8756e7..32716b3d0 100644
--- a/plans/changes_sync.go
+++ b/plans/changes_sync.go
@@ -16,3 +16,20 @@ type ChangesSync struct {
 	lock    sync.Mutex
 	changes *Changes
 }
+
+// AppendResourceInstanceChange records the given resource instance change in
+// the set of planned resource changes.
+//
+// The caller must ensure that there are no concurrent writes to the given
+// change while this method is running, but it is safe to resume mutating
+// it after this method returns without affecting the saved change.
+func (cs *ChangesSync) AppendResourceInstanceChange(changeSrc *ResourceInstanceChangeSrc) {
+	if cs == nil {
+		panic("AppendResourceInstanceChange on nil ChangesSync")
+	}
+	cs.lock.Lock()
+	defer cs.lock.Unlock()
+
+	s := changeSrc.DeepCopy()
+	cs.changes.Resources = append(cs.changes.Resources, s)
+}
diff --git a/plans/dynamic_value.go b/plans/dynamic_value.go
index fadf24312..91c1215b8 100644
--- a/plans/dynamic_value.go
+++ b/plans/dynamic_value.go
@@ -83,3 +83,14 @@ func (v DynamicValue) Decode(ty cty.Type) (cty.Value, error) {
 func (v DynamicValue) ImpliedType() (cty.Type, error) {
 	return ctymsgpack.ImpliedType([]byte(v))
 }
+
+// Copy produces a copy of the receiver with a distinct backing array.
+func (v DynamicValue) Copy() DynamicValue {
+	if len(v) == 0 {
+		return nil
+	}
+
+	ret := make(DynamicValue, len(v))
+	copy(ret, v)
+	return ret
+}
diff --git a/terraform/context.go b/terraform/context.go
index be4625551..a3df33c7c 100644
--- a/terraform/context.go
+++ b/terraform/context.go
@@ -718,6 +718,7 @@ func (c *Context) graphWalker(operation walkOperation) *ContextGraphWalker {
 	return &ContextGraphWalker{
 		Context:            c,
 		State:              c.state.SyncWrapper(),
+		Changes:            c.changes.SyncWrapper(),
 		Operation:          operation,
 		StopContext:        c.runContext,
 		RootVariableValues: c.variables,
diff --git a/terraform/eval_diff.go b/terraform/eval_diff.go
index 95f93410b..80b194faf 100644
--- a/terraform/eval_diff.go
+++ b/terraform/eval_diff.go
@@ -732,41 +732,40 @@ func (n *EvalReadDiff) Eval(ctx EvalContext) (interface{}, error) {
 // EvalWriteDiff is an EvalNode implementation that saves a planned change
 // for an instance object into the set of global planned changes.
 type EvalWriteDiff struct {
-	Addr       addrs.ResourceInstance
-	DeposedKey states.DeposedKey
-	Change     **plans.ResourceInstanceChange
+	Addr           addrs.ResourceInstance
+	DeposedKey     states.DeposedKey
+	ProviderSchema **ProviderSchema
+	Change         **plans.ResourceInstanceChange
 }
 
 // TODO: test
 func (n *EvalWriteDiff) Eval(ctx EvalContext) (interface{}, error) {
-	return nil, fmt.Errorf("EvalWriteDiff not yet updated for new plan types")
-	/*
-		diff, lock := ctx.Diff()
+	providerSchema := *n.ProviderSchema
+	change := *n.Change
 
-		// The diff to write, if its empty it should write nil
-		var diffVal *InstanceDiff
-		if n.Diff != nil {
-			diffVal = *n.Diff
-		}
-		if diffVal.Empty() {
-			diffVal = nil
-		}
+	if change.Addr.String() != n.Addr.String() || change.DeposedKey != n.DeposedKey {
+		// Should never happen, and indicates a bug in the caller.
+		panic("inconsistent address and/or deposed key in EvalWriteDiff")
+	}
 
-		// Acquire the lock so that we can do this safely concurrently
-		lock.Lock()
-		defer lock.Unlock()
+	schema := providerSchema.ResourceTypes[n.Addr.Resource.Type]
+	if schema == nil {
+		// Should be caught during validation, so we don't bother with a pretty error here
+		return nil, fmt.Errorf("provider does not support resource type %q", n.Addr.Resource.Type)
+	}
 
-		// Write the diff
-		modDiff := diff.ModuleByPath(ctx.Path())
-		if modDiff == nil {
-			modDiff = diff.AddModule(ctx.Path())
-		}
-		if diffVal != nil {
-			modDiff.Resources[n.Name] = diffVal
-		} else {
-			delete(modDiff.Resources, n.Name)
-		}
+	csrc, err := change.Encode(schema.ImpliedType())
+	if err != nil {
+		return nil, fmt.Errorf("failed to encode planned changes for %s: %s", n.Addr, err)
+	}
 
-		return nil, nil
-	*/
+	changes := ctx.Changes()
+	changes.AppendResourceInstanceChange(csrc)
+	if n.DeposedKey == states.NotDeposed {
+		log.Printf("[TRACE] EvalWriteDiff: recorded %s change for %s", change.Action, n.Addr)
+	} else {
+		log.Printf("[TRACE] EvalWriteDiff: recorded %s change for %s deposed object %s", change.Action, n.Addr, n.DeposedKey)
+	}
+
+	return nil, nil
 }
diff --git a/terraform/node_resource_apply.go b/terraform/node_resource_apply.go
index 80a0bce33..4ca75ae0b 100644
--- a/terraform/node_resource_apply.go
+++ b/terraform/node_resource_apply.go
@@ -181,8 +181,9 @@ func (n *NodeApplyableResourceInstance) evalTreeDataResource(addr addrs.AbsResou
 			// Clear the diff now that we've applied it, so
 			// later nodes won't see a diff that's now a no-op.
 			&EvalWriteDiff{
-				Addr:   addr.Resource,
-				Change: nil,
+				Addr:           addr.Resource,
+				ProviderSchema: &providerSchema,
+				Change:         nil,
 			},
 
 			&EvalUpdateStateHook{},
@@ -347,8 +348,9 @@ func (n *NodeApplyableResourceInstance) evalTreeManagedResource(addr addrs.AbsRe
 			// don't see a diff that is already complete. There
 			// is no longer a diff!
 			&EvalWriteDiff{
-				Addr:   addr.Resource,
-				Change: nil,
+				Addr:           addr.Resource,
+				ProviderSchema: &providerSchema,
+				Change:         nil,
 			},
 
 			&EvalApplyPost{
diff --git a/terraform/node_resource_plan_destroy.go b/terraform/node_resource_plan_destroy.go
index 22191d1e7..d978b6505 100644
--- a/terraform/node_resource_plan_destroy.go
+++ b/terraform/node_resource_plan_destroy.go
@@ -78,8 +78,9 @@ func (n *NodePlanDestroyableResourceInstance) EvalTree() EvalNode {
 				Change: &change,
 			},
 			&EvalWriteDiff{
-				Addr:   addr.Resource,
-				Change: &change,
+				Addr:           addr.Resource,
+				ProviderSchema: &providerSchema,
+				Change:         &change,
 			},
 		},
 	}
diff --git a/terraform/node_resource_plan_instance.go b/terraform/node_resource_plan_instance.go
index 217a4eaa7..31d35a333 100644
--- a/terraform/node_resource_plan_instance.go
+++ b/terraform/node_resource_plan_instance.go
@@ -99,8 +99,9 @@ func (n *NodePlannableResourceInstance) evalTreeDataResource(addr addrs.AbsResou
 			},
 
 			&EvalWriteDiff{
-				Addr:   addr.Resource,
-				Change: &change,
+				Addr:           addr.Resource,
+				ProviderSchema: &providerSchema,
+				Change:         &change,
 			},
 		},
 	}
@@ -157,8 +158,9 @@ func (n *NodePlannableResourceInstance) evalTreeManagedResource(addr addrs.AbsRe
 				ProviderSchema: &providerSchema,
 			},
 			&EvalWriteDiff{
-				Addr:   addr.Resource,
-				Change: &change,
+				Addr:           addr.Resource,
+				ProviderSchema: &providerSchema,
+				Change:         &change,
 			},
 		},
 	}
diff --git a/terraform/node_resource_plan_orphan.go b/terraform/node_resource_plan_orphan.go
index 8f5328375..fddd465e6 100644
--- a/terraform/node_resource_plan_orphan.go
+++ b/terraform/node_resource_plan_orphan.go
@@ -68,8 +68,9 @@ func (n *NodePlannableResourceInstanceOrphan) EvalTree() EvalNode {
 				Change: &change,
 			},
 			&EvalWriteDiff{
-				Addr:   addr.Resource,
-				Change: &change,
+				Addr:           addr.Resource,
+				ProviderSchema: &providerSchema,
+				Change:         &change,
 			},
 			&EvalWriteState{
 				Addr:           addr.Resource,