diff --git a/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts b/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts
index 572cfdd..e686c9e 100644
--- a/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts
+++ b/implementations/javascript/packages/schema/src/bin/preserves-schema-ts.ts
@@ -80,6 +80,10 @@ export function modulePathTo(file1: string, file2: string): string {
     return changeExt(naive, '');
 }
 
+function isAbsoluteOrExplicitlyRelative(p: string) {
+    return p[0] === '.' || p[0] === '/';
+}
+
 export function runOnce(options: CommandLineArguments): CompilationResult {
     const { base, failures, inputFiles: inputFiles0 } =
         expandInputGlob(options.inputs, options.base);
@@ -106,7 +110,9 @@ export function runOnce(options: CommandLineArguments): CompilationResult {
     inputFiles.forEach(c => {
         const env: M.Environment = [
             ... extensionEnv.flatMap(e => {
-                const p = modulePathTo(c.outputFilePath, e.typescriptModulePath);
+                const p = isAbsoluteOrExplicitlyRelative(e.typescriptModulePath)
+                    ? modulePathTo(c.outputFilePath, e.typescriptModulePath)
+                    : e.typescriptModulePath /* assuming it names something in node_modules */;
                 if (p === null) return [];
                 return [{... e, typescriptModulePath: p}];
             }),