diff --git a/src/printer.js b/src/printer.js
index d440df1d3..71e96ec6c 100644
--- a/src/printer.js
+++ b/src/printer.js
@@ -1974,6 +1974,11 @@ function genericPrintNoParens(path, options, print, args) {
         ") => ",
         path.call(print, "typeAnnotation"),
       ])
+    case "TSTypeOperator":
+      return concat([
+        "keyof ",
+        path.call(print, "typeAnnotation")
+      ])
     // TODO
     case "ClassHeritage":
     // TODO
diff --git a/tests/typescript/conformance/types/typeOperator/__snapshots__/jsfmt.spec.js.snap b/tests/typescript/conformance/types/typeOperator/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 000000000..c5004ade7
--- /dev/null
+++ b/tests/typescript/conformance/types/typeOperator/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,8 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`typeOperator.ts 1`] = `
+let a: (keyof T)[] = ["a", "b"];
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+let a: (keyof T)[] = ["a", "b"];
+
+`;
diff --git a/tests/typescript/conformance/types/typeOperator/jsfmt.spec.js b/tests/typescript/conformance/types/typeOperator/jsfmt.spec.js
new file mode 100644
index 000000000..bc085c48c
--- /dev/null
+++ b/tests/typescript/conformance/types/typeOperator/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, { parser: "typescript" });
diff --git a/tests/typescript/conformance/types/typeOperator/typeOperator.ts b/tests/typescript/conformance/types/typeOperator/typeOperator.ts
new file mode 100644
index 000000000..36813dc2f
--- /dev/null
+++ b/tests/typescript/conformance/types/typeOperator/typeOperator.ts
@@ -0,0 +1 @@
+let a: (keyof T)[] = ["a", "b"];