diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 8bb65e57616..1da70cd173f 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -1012,8 +1012,10 @@ namespace ts {
                 }
                 else {
                     const jsPath = tryReadPackageJsonFields(/*readTypes*/ false, packageJsonContent, nodeModuleDirectory, state);
-                    if (typeof jsPath === "string") {
-                        subModuleName = removeExtension(removeExtension(jsPath.substring(nodeModuleDirectory.length + 1), Extension.Js), Extension.Jsx) + Extension.Dts;
+                    if (typeof jsPath === "string" && jsPath.length > nodeModuleDirectory.length) {
+                        const potentialSubModule = jsPath.substring(nodeModuleDirectory.length + 1);
+                        subModuleName = (forEach(supportedJavascriptExtensions, extension =>
+                            tryRemoveExtension(potentialSubModule, extension)) || potentialSubModule) + Extension.Dts;
                     }
                     else {
                         subModuleName = "index.d.ts";
diff --git a/tests/baselines/reference/moduleResolution_packageJson_yesAtPackageRoot_mainFieldInSubDirectory.trace.json b/tests/baselines/reference/moduleResolution_packageJson_yesAtPackageRoot_mainFieldInSubDirectory.trace.json
index d02e83a9a70..4833e4a57a0 100644
--- a/tests/baselines/reference/moduleResolution_packageJson_yesAtPackageRoot_mainFieldInSubDirectory.trace.json
+++ b/tests/baselines/reference/moduleResolution_packageJson_yesAtPackageRoot_mainFieldInSubDirectory.trace.json
@@ -5,7 +5,7 @@
     "'package.json' does not have a 'typings' field.",
     "'package.json' does not have a 'types' field.",
     "'package.json' has 'main' field 'src/index.js' that references '/node_modules/foo/src/index.js'.",
-    "Found 'package.json' at '/node_modules/foo/package.json'. Package ID is 'foo/src/i.d.ts@1.2.3'.",
+    "Found 'package.json' at '/node_modules/foo/package.json'. Package ID is 'foo/src/index.d.ts@1.2.3'.",
     "File '/node_modules/foo.ts' does not exist.",
     "File '/node_modules/foo.tsx' does not exist.",
     "File '/node_modules/foo.d.ts' does not exist.",
@@ -19,7 +19,7 @@
     "'package.json' does not have a 'typings' field.",
     "'package.json' does not have a 'types' field.",
     "'package.json' has 'main' field 'src/index.js' that references '/node_modules/foo/src/index.js'.",
-    "Found 'package.json' at '/node_modules/foo/package.json'. Package ID is 'foo/src/i.d.ts@1.2.3'.",
+    "Found 'package.json' at '/node_modules/foo/package.json'. Package ID is 'foo/src/index.d.ts@1.2.3'.",
     "File '/node_modules/foo.js' does not exist.",
     "File '/node_modules/foo.jsx' does not exist.",
     "'package.json' has 'main' field 'src/index.js' that references '/node_modules/foo/src/index.js'.",