diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index c009cc69..b935cc70 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -12,7 +12,7 @@ jobs:
   test:
     strategy:
       matrix:
-        os: [ubuntu-latest, macOS-latest]
+        os: [ubuntu-latest, macOS-latest, windows-latest]
         node-version: [18, 20]
     runs-on: ${{ matrix.os }}
 
diff --git a/lib/classes/asset.js b/lib/classes/asset.js
index bb761941..4e23b9bb 100644
--- a/lib/classes/asset.js
+++ b/lib/classes/asset.js
@@ -1,5 +1,6 @@
 import mime from "mime";
 import path from "node:path";
+import { toUrlPathname } from "../utils/url.js";
 
 /**
  * @typedef {object} AssetOptions
@@ -31,7 +32,7 @@ const Asset = class Asset {
 		this._size = -1;
 
 		this._integrity = "";
-		this._pathname = path.join("/", pathname);
+		this._pathname = toUrlPathname(path.join("/", pathname));
 		this._version = version;
 		this._name = name;
 		this._org = org;
diff --git a/lib/sinks/test.js b/lib/sinks/test.js
index 2d5f1c2e..d76cdaab 100644
--- a/lib/sinks/test.js
+++ b/lib/sinks/test.js
@@ -4,7 +4,7 @@ import Metrics from "@metrics/client";
 import Sink from "@eik/sink";
 import mime from "mime";
 import path from "node:path";
-
+import { toUrlPathname } from "../utils/url.js";
 import Entry from "./mem-entry.js";
 
 const DEFAULT_ROOT_PATH = "/eik";
@@ -41,7 +41,7 @@ export default class SinkTest extends Sink {
 	}
 
 	set(filePath, payload) {
-		const pathname = path.join(this._rootPath, filePath);
+		const pathname = toUrlPathname(path.join(this._rootPath, filePath));
 		const mimeType = mime.getType(pathname) || "application/octet-stream";
 
 		let entry;
@@ -56,7 +56,7 @@ export default class SinkTest extends Sink {
 	}
 
 	get(filePath) {
-		const pathname = path.join(this._rootPath, filePath);
+		const pathname = toUrlPathname(path.join(this._rootPath, filePath));
 		if (this._state.has(pathname)) {
 			const entry = this._state.get(pathname);
 			return entry.payload.join("");
@@ -110,7 +110,7 @@ export default class SinkTest extends Sink {
 				return;
 			}
 
-			const pathname = path.join(this._rootPath, filePath);
+			const pathname = toUrlPathname(path.join(this._rootPath, filePath));
 
 			if (pathname.indexOf(this._rootPath) !== 0) {
 				this._counter.inc({ labels: { operation } });
@@ -178,7 +178,7 @@ export default class SinkTest extends Sink {
 				return;
 			}
 
-			const pathname = path.join(this._rootPath, filePath);
+			const pathname = toUrlPathname(path.join(this._rootPath, filePath));
 
 			if (pathname.indexOf(this._rootPath) !== 0) {
 				this._counter.inc({ labels: { operation } });
@@ -228,7 +228,7 @@ export default class SinkTest extends Sink {
 				return;
 			}
 
-			const pathname = path.join(this._rootPath, filePath);
+			const pathname = toUrlPathname(path.join(this._rootPath, filePath));
 
 			if (pathname.indexOf(this._rootPath) !== 0) {
 				this._counter.inc({ labels: { operation } });
@@ -267,7 +267,7 @@ export default class SinkTest extends Sink {
 				return;
 			}
 
-			const pathname = path.join(this._rootPath, filePath);
+			const pathname = toUrlPathname(path.join(this._rootPath, filePath));
 
 			if (pathname.indexOf(this._rootPath) !== 0) {
 				this._counter.inc({ labels: { operation } });
diff --git a/lib/utils/path-builders-uri.js b/lib/utils/path-builders-uri.js
index dce4d72b..145bea3a 100644
--- a/lib/utils/path-builders-uri.js
+++ b/lib/utils/path-builders-uri.js
@@ -1,38 +1,31 @@
 import path from "node:path";
 import globals from "./globals.js";
-
-// Build URL pathname to a package log file
+import { toUrlPathname } from "./url.js";
 
 const createURIPathToPkgLog = ({ type = "", name = "", version = "" } = {}) =>
-	path.join(globals.ROOT, type, name, version);
-
-// Build URL pathname to an asset in a package
+	toUrlPathname(path.join(globals.ROOT, type, name, version));
 
 const createURIPathToAsset = ({
 	type = "",
 	name = "",
 	version = "",
 	asset = "",
-} = {}) => path.join(globals.ROOT, type, name, version, asset);
-
-// Build URL pathname to an import map
+} = {}) => toUrlPathname(path.join(globals.ROOT, type, name, version, asset));
 
 const createURIPathToImportMap = ({ name = "", version = "" } = {}) =>
-	path.join(globals.ROOT, globals.BASE_IMPORT_MAPS, name, version);
-
-// Build URL pathname to an alias source
+	toUrlPathname(
+		path.join(globals.ROOT, globals.BASE_IMPORT_MAPS, name, version),
+	);
 
 const createURIToAlias = ({ type = "", name = "", alias = "" } = {}) =>
-	path.join(globals.ROOT, type, name, `v${alias}`);
-
-// Build URL pathname to an alias target destination
+	toUrlPathname(path.join(globals.ROOT, type, name, `v${alias}`));
 
 const createURIToTargetOfAlias = ({
 	type = "",
 	name = "",
 	version = "",
 	extra = "",
-} = {}) => path.join(globals.ROOT, type, name, version, extra);
+} = {}) => toUrlPathname(path.join(globals.ROOT, type, name, version, extra));
 
 export {
 	createURIPathToPkgLog,
diff --git a/lib/utils/url.js b/lib/utils/url.js
new file mode 100644
index 00000000..91e931cc
--- /dev/null
+++ b/lib/utils/url.js
@@ -0,0 +1,8 @@
+/**
+ * Takes a pathname that may have win32 separators and ensures it's ready to be used as a URI
+ * @param {string} pathname
+ * @returns {string}
+ */
+export function toUrlPathname(pathname) {
+	return pathname.replace(/\\/g, "/");
+}
diff --git a/package.json b/package.json
index d173f003..22265d03 100644
--- a/package.json
+++ b/package.json
@@ -25,7 +25,7 @@
   "author": "",
   "license": "MIT",
   "dependencies": {
-    "@eik/common": "4.1.0",
+    "@eik/common": "4.1.1",
     "@eik/sink": "1.2.5",
     "@eik/sink-file-system": "1.0.1",
     "@eik/sink-memory": "1.1.2",