diff --git a/terraform/state_add.go b/terraform/state_add.go
index b837e8f57..445ba2ab8 100644
--- a/terraform/state_add.go
+++ b/terraform/state_add.go
@@ -98,7 +98,11 @@ func stateAddFunc_Resource_Resource(s *State, addr *ResourceAddress, raw interfa
 	src := raw.(*ResourceState)
 
 	// Initialize the resource
-	resource := stateAddInitAddr(s, addr).(*ResourceState)
+	resourceRaw, exists := stateAddInitAddr(s, addr)
+	if exists {
+		return fmt.Errorf("resource exists and not empty: %s", addr)
+	}
+	resource := resourceRaw.(*ResourceState)
 	resource.Type = src.Type
 
 	// TODO: Dependencies
@@ -218,17 +222,19 @@ func detectValueAddLoc(raw interface{}) stateAddLoc {
 // stateAddInitAddr takes a ResourceAddress and creates the non-existing
 // resources up to that point, returning the empty (or existing) interface
 // at that address.
-func stateAddInitAddr(s *State, addr *ResourceAddress) interface{} {
+func stateAddInitAddr(s *State, addr *ResourceAddress) (interface{}, bool) {
 	addType := detectAddrAddLoc(addr)
 
 	// Get the module
 	path := append([]string{"root"}, addr.Path...)
+	exists := true
 	mod := s.ModuleByPath(path)
 	if mod == nil {
 		mod = s.AddModule(path)
+		exists = false
 	}
 	if addType == stateAddModule {
-		return mod
+		return mod, exists
 	}
 
 	// Add the resource
@@ -237,17 +243,20 @@ func stateAddInitAddr(s *State, addr *ResourceAddress) interface{} {
 		Type:  addr.Type,
 		Index: addr.Index,
 	}).String()
+	exists = true
 	resource, ok := mod.Resources[resourceKey]
 	if !ok {
 		resource = &ResourceState{Type: addr.Type}
 		resource.init()
 		mod.Resources[resourceKey] = resource
+		exists = false
 	}
 	if addType == stateAddResource {
-		return resource
+		return resource, exists
 	}
 
 	// Get the instance
+	exists = true
 	var instance *InstanceState
 	switch addr.InstanceType {
 	case TypePrimary:
@@ -271,7 +280,8 @@ func stateAddInitAddr(s *State, addr *ResourceAddress) interface{} {
 	}
 	if instance == nil {
 		instance = &InstanceState{}
+		exists = false
 	}
 
-	return instance
+	return instance, exists
 }
diff --git a/terraform/state_add_test.go b/terraform/state_add_test.go
index 9cd54457e..54944258f 100644
--- a/terraform/state_add_test.go
+++ b/terraform/state_add_test.go
@@ -162,6 +162,34 @@ func TestStateAdd(t *testing.T) {
 				},
 			},
 		},
+
+		"ResourceState => Resource Addr (existing)": {
+			true,
+			"aws_instance.foo",
+			&ResourceState{
+				Type: "test_instance",
+				Primary: &InstanceState{
+					ID: "foo",
+				},
+			},
+
+			&State{
+				Modules: []*ModuleState{
+					&ModuleState{
+						Path: []string{"root"},
+						Resources: map[string]*ResourceState{
+							"aws_instance.foo": &ResourceState{
+								Type: "test_instance",
+								Primary: &InstanceState{
+									ID: "foo",
+								},
+							},
+						},
+					},
+				},
+			},
+			nil,
+		},
 	}
 
 	for k, tc := range cases {