diff --git a/packages/babel-plugin-transform-parameters/src/params.js b/packages/babel-plugin-transform-parameters/src/params.js
index 0a85bfbd884c..2f2a8da1450c 100644
--- a/packages/babel-plugin-transform-parameters/src/params.js
+++ b/packages/babel-plugin-transform-parameters/src/params.js
@@ -36,6 +36,9 @@ const iifeVisitor = {
       path.stop();
     }
   },
+  // type annotations don't use or introduce "real" bindings
+  "TypeAnnotation|TSTypeAnnotation|TypeParameterDeclaration|TSTypeParameterDeclaration": path =>
+    path.skip(),
 };
 
 export default function convertFunctionParams(path, loose) {
diff --git a/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/input.js b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/input.js
new file mode 100644
index 000000000000..953d0473e286
--- /dev/null
+++ b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/input.js
@@ -0,0 +1,7 @@
+function a(b: (c) => void = {}) {
+  let c;
+}
+
+function d(e = <T>() => {}) {
+  let T;
+}
diff --git a/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/options.json b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/options.json
new file mode 100644
index 000000000000..8fe7e8dceccb
--- /dev/null
+++ b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/options.json
@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    "transform-parameters",
+    "syntax-flow"
+  ]
+}
diff --git a/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/output.js b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/output.js
new file mode 100644
index 000000000000..d4d757d31d0d
--- /dev/null
+++ b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-flow/output.js
@@ -0,0 +1,9 @@
+function a() {
+  let b: (c) => void = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
+  let c;
+}
+
+function d() {
+  let e = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : <T>() => {};
+  let T;
+}
diff --git a/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/input.js b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/input.js
new file mode 100644
index 000000000000..953d0473e286
--- /dev/null
+++ b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/input.js
@@ -0,0 +1,7 @@
+function a(b: (c) => void = {}) {
+  let c;
+}
+
+function d(e = <T>() => {}) {
+  let T;
+}
diff --git a/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/options.json b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/options.json
new file mode 100644
index 000000000000..abf00ef61215
--- /dev/null
+++ b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/options.json
@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    "transform-parameters",
+    "syntax-typescript"
+  ]
+}
diff --git a/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/output.js b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/output.js
new file mode 100644
index 000000000000..d4d757d31d0d
--- /dev/null
+++ b/packages/babel-plugin-transform-parameters/test/fixtures/regression/11344-typescript/output.js
@@ -0,0 +1,9 @@
+function a() {
+  let b: (c) => void = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
+  let c;
+}
+
+function d() {
+  let e = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : <T>() => {};
+  let T;
+}