diff --git a/src/transformers/JSXTransformer.ts b/src/transformers/JSXTransformer.ts
index 09bac056..3e96524f 100644
--- a/src/transformers/JSXTransformer.ts
+++ b/src/transformers/JSXTransformer.ts
@@ -3,6 +3,7 @@ import {Options} from "../index";
 import NameManager from "../NameManager";
 import XHTMLEntities from "../parser/plugins/jsx/xhtml";
 import {TokenType as tt} from "../parser/tokenizer/types";
+import {charCodes} from "../parser/util/charcodes";
 import TokenProcessor from "../TokenProcessor";
 import getJSXPragmaInfo, {JSXPragmaInfo} from "../util/getJSXPragmaInfo";
 import RootTransformer from "./RootTransformer";
@@ -252,7 +253,8 @@ export default class JSXTransformer extends Transformer {
 }
 
 export function startsWithLowerCase(s: string): boolean {
-  return s[0] === s[0].toLowerCase();
+  const firstChar = s.charCodeAt(0);
+  return firstChar >= charCodes.lowercaseA && firstChar <= charCodes.lowercaseZ;
 }
 
 /**
diff --git a/test/jsx-test.ts b/test/jsx-test.ts
index d8f237ba..b5c9044d 100644
--- a/test/jsx-test.ts
+++ b/test/jsx-test.ts
@@ -37,6 +37,17 @@ describe("transform JSX", () => {
     );
   });
 
+  it("handles component names starting with _", () => {
+    assertResult(
+      `
+      <_Foo />
+    `,
+      `${JSX_PREFIX}
+      React.createElement(_Foo, {${devProps(2)}} )
+    `,
+    );
+  });
+
   it("transforms nested JSX elements", () => {
     assertResult(
       `