diff --git a/packages/babel-generator/src/generators/flow.js b/packages/babel-generator/src/generators/flow.js
index 156c0114ec..92f80deb24 100644
--- a/packages/babel-generator/src/generators/flow.js
+++ b/packages/babel-generator/src/generators/flow.js
@@ -420,9 +420,11 @@ export function ObjectTypeIndexer(node: Object) {
   }
   this._variance(node);
   this.token("[");
-  this.print(node.id, node);
-  this.token(":");
-  this.space();
+  if (node.id) {
+    this.print(node.id, node);
+    this.token(":");
+    this.space();
+  }
   this.print(node.key, node);
   this.token("]");
   this.token(":");
diff --git a/packages/babel-generator/test/fixtures/flow/object-literal-types/actual.js b/packages/babel-generator/test/fixtures/flow/object-literal-types/actual.js
index e7c44cbd0f..6d747ee65e 100644
--- a/packages/babel-generator/test/fixtures/flow/object-literal-types/actual.js
+++ b/packages/babel-generator/test/fixtures/flow/object-literal-types/actual.js
@@ -7,3 +7,5 @@ type T = { ...U, p: V, };
 type T = { ...{}|{ p: V, }};
 type T = { foo(): number }
 type T = { foo: () => number }
+type T = { [string]: U };
+type T = { [param: string]: U };
diff --git a/packages/babel-generator/test/fixtures/flow/object-literal-types/expected.js b/packages/babel-generator/test/fixtures/flow/object-literal-types/expected.js
index 4eb91613ba..e394e17da3 100644
--- a/packages/babel-generator/test/fixtures/flow/object-literal-types/expected.js
+++ b/packages/babel-generator/test/fixtures/flow/object-literal-types/expected.js
@@ -22,3 +22,9 @@ type T = {
 type T = {
   foo: () => number
 };
+type T = {
+  [string]: U
+};
+type T = {
+  [param: string]: U
+};