diff --git a/packages/babel-plugin-flow-runtime/src/__tests__/__fixtures__/bugs/180-type-parameter-assert-false.js b/packages/babel-plugin-flow-runtime/src/__tests__/__fixtures__/bugs/180-type-parameter-assert-false.js
new file mode 100644
index 0000000..ef08d39
--- /dev/null
+++ b/packages/babel-plugin-flow-runtime/src/__tests__/__fixtures__/bugs/180-type-parameter-assert-false.js
@@ -0,0 +1,40 @@
+/* @flow */
+
+export const input = `
+  function foo<X>() {
+    let bar: X;
+  }
+`;
+
+export const expected = `
+  import t from "flow-runtime";
+  function foo() {
+    const X = t.typeParameter("X");
+    let _barType = X,
+        bar;
+  }
+`;
+
+export const annotated = `
+  import t from "flow-runtime";
+  function foo() {
+    let bar;
+  }
+  t.annotate(foo, t.function(_fn => {
+    const X = _fn.typeParameter("X");
+    return [];
+  }));
+`;
+
+export const combined = `
+  import t from "flow-runtime";
+  function foo() {
+    const X = t.typeParameter("X");
+    let _barType = X,
+        bar;
+  }
+  t.annotate(foo, t.function(_fn => {
+    const X = _fn.typeParameter("X");
+    return [];
+  }));
+`;
diff --git a/packages/babel-plugin-flow-runtime/src/transformVisitors.js b/packages/babel-plugin-flow-runtime/src/transformVisitors.js
index e88d0f7..90d1ca3 100644
--- a/packages/babel-plugin-flow-runtime/src/transformVisitors.js
+++ b/packages/babel-plugin-flow-runtime/src/transformVisitors.js
@@ -233,6 +233,10 @@ export default function transformVisitors (context: ConversionContext): Object {
       }
       const {name} = id.node;
 
+      if (!shouldCheck) {
+        return;
+      }
+
       if (!path.has('init') || path.parentPath.node.kind !== 'const') {
         const valueUid = path.scope.generateUidIdentifier(`${name}Type`);
         path.scope.setData(`valueUid:${name}`, valueUid);
@@ -263,7 +267,7 @@ export default function transformVisitors (context: ConversionContext): Object {
           ));
         }
 
-        if (shouldCheck && path.has('init')) {
+        if (path.has('init')) {
           const wrapped = context.assert(
             valueUid,
             path.get('init').node
@@ -276,7 +280,7 @@ export default function transformVisitors (context: ConversionContext): Object {
           ));
         }
       }
-      else if (shouldCheck) {
+      else {
         const wrapped = context.assert(
           convert(context, id.get('typeAnnotation')),
           path.get('init').node