diff --git a/src/language-js/print/union-type.js b/src/language-js/print/union-type.js
index 0b1da7ab9..34e26a49e 100644
--- a/src/language-js/print/union-type.js
+++ b/src/language-js/print/union-type.js
@@ -97,7 +97,11 @@ function shouldIndentUnionType(path) {
     (key === "elementTypes" && isTupleType(parent)) ||
     ((key === "trueType" || key === "falseType") &&
       isConditionalType(parent)) ||
-    (key === "params" && isTypeParameterInstantiation(parent))
+    (key === "params" && isTypeParameterInstantiation(parent)) ||
+    (key === "typeAnnotation" &&
+      parent.type === "FunctionTypeParam" &&
+      !parent.name &&
+      path.grandparent.this !== parent)
   ) {
     return false;
   }
diff --git a/tests/format/flow/this-annotation/__snapshots__/format.test.js.snap b/tests/format/flow/this-annotation/__snapshots__/format.test.js.snap
index 1d7877785..264541e52 100644
--- a/tests/format/flow/this-annotation/__snapshots__/format.test.js.snap
+++ b/tests/format/flow/this-annotation/__snapshots__/format.test.js.snap
@@ -176,32 +176,54 @@ trailingComma: "all"
 =====================================input======================================
 // @flow
 
-type A = (
-  this: | SupperLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+type A1 = (
+  this: | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
   b: number,
 ) => boolean;
 
-type B = (
-  _this: | SupperLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+type A2 = (
+  _this: | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+  b: number,
+) => boolean
+
+type A3 = (
+  | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+  b: number,
+) => boolean
+
+type A4 = (
+  /* this: */ | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
   b: number,
 ) => boolean
 
 =====================================output=====================================
 // @flow
 
-type A = (
+type A1 = (
   this:
-    | SupperLongLongLongLongLongLongLongLongLongLongLongType
+    | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType
     | FooBarBazLorem12345,
   b: number,
 ) => boolean;
 
-type B = (
+type A2 = (
   _this:
-    | SupperLongLongLongLongLongLongLongLongLongLongLongType
+    | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType
     | FooBarBazLorem12345,
   b: number,
 ) => boolean;
 
+type A3 = (
+  | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType
+  | FooBarBazLorem12345,
+  b: number,
+) => boolean;
+
+type A4 = (
+  /* this: */ | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType
+  | FooBarBazLorem12345,
+  b: number,
+) => boolean;
+
 ================================================================================
 `;
diff --git a/tests/format/flow/this-annotation/union_type.js b/tests/format/flow/this-annotation/union_type.js
index cf502b970..3260ea5df 100644
--- a/tests/format/flow/this-annotation/union_type.js
+++ b/tests/format/flow/this-annotation/union_type.js
@@ -1,11 +1,21 @@
 // @flow
 
-type A = (
-  this: | SupperLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+type A1 = (
+  this: | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
   b: number,
 ) => boolean;
 
-type B = (
-  _this: | SupperLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+type A2 = (
+  _this: | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+  b: number,
+) => boolean
+
+type A3 = (
+  | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
+  b: number,
+) => boolean
+
+type A4 = (
+  /* this: */ | SupperLongLongLongLongLongLongLongLongLongLongLongLongLongType | FooBarBazLorem12345,
   b: number,
 ) => boolean
diff --git a/tests/format/flow/union/__snapshots__/format.test.js.snap b/tests/format/flow/union/__snapshots__/format.test.js.snap
index 427fc17a9..4f9575673 100644
--- a/tests/format/flow/union/__snapshots__/format.test.js.snap
+++ b/tests/format/flow/union/__snapshots__/format.test.js.snap
@@ -22,6 +22,85 @@ const myValue = (callcallcallcallcallcall(
 ================================================================================
 `;
 
+exports[`function-type-param.js format 1`] = `
+====================================options=====================================
+parsers: ["flow"]
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+type a1 = (
+    | {//
+      }
+    | {//
+      },
+  ) => void
+
+type a2 = (
+// Comment
+    | {//
+      }
+    | {//
+      },
+  ) => void
+
+hook useRefetchFunction(
+  dispatch: (
+    | {
+        environment: IEnvironment,
+        fragmentIdentifier: string,
+        type: 'reset',
+      }
+    | {
+        fetchPolicy?: FetchPolicy,
+        onComplete?: (Error | null) => void,
+        refetchEnvironment: ?IEnvironment,
+        refetchQuery: OperationDescriptor,
+        renderPolicy?: RenderPolicy,
+        type: 'refetch',
+      },
+  ) => void,
+) {}
+
+=====================================output=====================================
+type a1 = (
+  | {
+      //
+    }
+  | {
+      //
+    },
+) => void;
+
+type a2 = (
+  // Comment
+  | {
+      //
+    }
+  | {
+      //
+    },
+) => void;
+
+hook useRefetchFunction(
+  dispatch: (
+    | {
+        environment: IEnvironment,
+        fragmentIdentifier: string,
+        type: "reset",
+      }
+    | {
+        fetchPolicy?: FetchPolicy,
+        onComplete?: (Error | null) => void,
+        refetchEnvironment: ?IEnvironment,
+        refetchQuery: OperationDescriptor,
+        renderPolicy?: RenderPolicy,
+        type: "refetch",
+      },
+  ) => void,
+) {}
+
+================================================================================
+`;
+
 exports[`issue-1197-2.js format 1`] = `
 ====================================options=====================================
 parsers: ["flow"]
diff --git a/tests/format/flow/union/function-type-param.js b/tests/format/flow/union/function-type-param.js
new file mode 100644
index 000000000..d0b50e27e
--- /dev/null
+++ b/tests/format/flow/union/function-type-param.js
@@ -0,0 +1,32 @@
+type a1 = (
+    | {//
+      }
+    | {//
+      },
+  ) => void
+
+type a2 = (
+// Comment
+    | {//
+      }
+    | {//
+      },
+  ) => void
+
+hook useRefetchFunction(
+  dispatch: (
+    | {
+        environment: IEnvironment,
+        fragmentIdentifier: string,
+        type: 'reset',
+      }
+    | {
+        fetchPolicy?: FetchPolicy,
+        onComplete?: (Error | null) => void,
+        refetchEnvironment: ?IEnvironment,
+        refetchQuery: OperationDescriptor,
+        renderPolicy?: RenderPolicy,
+        type: 'refetch',
+      },
+  ) => void,
+) {}
diff --git a/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap b/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap
index fc3350529..21eff6eb5 100644
--- a/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap
+++ b/tests/format/typescript/union/consistent-with-flow/__snapshots__/format.test.js.snap
@@ -257,6 +257,52 @@ type A = T extends "arrow"
 ================================================================================
 `;
 
+exports[`function-type-param.ts format 1`] = `
+====================================options=====================================
+parsers: ["typescript", "flow"]
+                                                      printWidth: 80 (default) |
+=====================================input======================================
+type a1 = (
+  a:  | {//
+      }
+    | {//
+      },
+  ) => void
+
+type a2 = (
+a:
+// Comment
+    | {//
+      }
+    | {//
+      },
+  ) => void
+
+=====================================output=====================================
+type a1 = (
+  a:
+    | {
+        //
+      }
+    | {
+        //
+      },
+) => void;
+
+type a2 = (
+  a:
+    // Comment
+    | {
+        //
+      }
+    | {
+        //
+      },
+) => void;
+
+================================================================================
+`;
+
 exports[`in-tuple.ts format 1`] = `
 ====================================options=====================================
 parsers: ["typescript", "flow"]
diff --git a/tests/format/typescript/union/consistent-with-flow/function-type-param.ts b/tests/format/typescript/union/consistent-with-flow/function-type-param.ts
new file mode 100644
index 000000000..ad7f70042
--- /dev/null
+++ b/tests/format/typescript/union/consistent-with-flow/function-type-param.ts
@@ -0,0 +1,15 @@
+type a1 = (
+  a:  | {//
+      }
+    | {//
+      },
+  ) => void
+
+type a2 = (
+a:
+// Comment
+    | {//
+      }
+    | {//
+      },
+  ) => void