diff --git a/src/transpilation/resolve.ts b/src/transpilation/resolve.ts
index 558870f21..781da43c2 100644
--- a/src/transpilation/resolve.ts
+++ b/src/transpilation/resolve.ts
@@ -341,6 +341,9 @@ function replaceRequireInSourceMap(
 }
 
 function requirePathForFile(filePath: string, extension = ".lua"): string {
+    if (!extension.startsWith(".")) {
+        extension = `.${extension}`;
+    }
     if (filePath.endsWith(extension)) {
         return formatPathToLuaPath(filePath.substring(0, filePath.length - extension.length));
     } else {
diff --git a/test/transpile/module-resolution.spec.ts b/test/transpile/module-resolution.spec.ts
index f95771687..7aa96001a 100644
--- a/test/transpile/module-resolution.spec.ts
+++ b/test/transpile/module-resolution.spec.ts
@@ -182,6 +182,14 @@ describe("module resolution with sourceDir", () => {
             .setOptions({ outDir: "tstl-out", extension: ".script" })
             .expectToEqual(expectedResult);
     });
+
+    // https://github.com/TypeScriptToLua/TypeScriptToLua/issues/1394
+    test("can resolve files with non-standard extension without separator (#1394)", () => {
+        util.testProject(path.join(projectPath, "tsconfig.json"))
+            .setMainFileName(path.join(projectPath, "src", "main.ts"))
+            .setOptions({ outDir: "tstl-out", extension: "script" })
+            .expectToEqual(expectedResult);
+    });
 });
 
 describe("module resolution project with lua sources", () => {
diff --git a/test/util.ts b/test/util.ts
index c86d40453..1b41bb4a2 100644
--- a/test/util.ts
+++ b/test/util.ts
@@ -468,7 +468,10 @@ end)());`;
     }
 
     private injectLuaFile(state: LuaState, lua: Lua, lauxlib: LauxLib, fileName: string, fileContent: string) {
-        const extension = this.options.extension ?? ".lua";
+        let extension = this.options.extension ?? ".lua";
+        if (!extension.startsWith(".")) {
+            extension = `.${extension}`;
+        }
         const modName = fileName.endsWith(extension)
             ? formatPathToLuaPath(fileName.substring(0, fileName.length - extension.length))
             : fileName;