diff --git a/src/language-js/printer-estree.js b/src/language-js/printer-estree.js
index ab57ee5b3c48..6d0d8c8b356b 100644
--- a/src/language-js/printer-estree.js
+++ b/src/language-js/printer-estree.js
@@ -3118,6 +3118,7 @@ function printPathNoParens(path, options, print, args) {
         n.accessibility ? concat([n.accessibility, " "]) : "",
         n.static ? "static " : "",
         n.readonly ? "readonly " : "",
+        n.declare ? "declare " : "",
         "[",
         n.parameters ? parametersGroup : "",
         n.typeAnnotation ? "]: " : "]",
diff --git a/tests/misc/typescript-babel-only/__snapshots__/jsfmt.spec.js.snap b/tests/misc/typescript-babel-only/__snapshots__/jsfmt.spec.js.snap
index 42500d9ead56..2d7dba38a3f5 100644
--- a/tests/misc/typescript-babel-only/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/misc/typescript-babel-only/__snapshots__/jsfmt.spec.js.snap
@@ -1,5 +1,25 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`declare-index-signature.ts format 1`] = `
+====================================options=====================================
+parsers: ["babel-ts"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+// Invalid, but recoverable
+class C {
+  declare [key: string]: string;
+}
+
+=====================================output=====================================
+// Invalid, but recoverable
+class C {
+  declare [key: string]: string;
+}
+
+================================================================================
+`;
+
 exports[`tuple-labeled-ts.ts format 1`] = `
 ====================================options=====================================
 parsers: ["babel-ts"]
diff --git a/tests/misc/typescript-babel-only/declare-index-signature.ts b/tests/misc/typescript-babel-only/declare-index-signature.ts
new file mode 100644
index 000000000000..2ba1b7e1c876
--- /dev/null
+++ b/tests/misc/typescript-babel-only/declare-index-signature.ts
@@ -0,0 +1,4 @@
+// Invalid, but recoverable
+class C {
+  declare [key: string]: string;
+}