diff --git a/lib/manifest.js b/lib/manifest.js
index 51db3ff..544043d 100644
--- a/lib/manifest.js
+++ b/lib/manifest.js
@@ -12,6 +12,7 @@ exports.Manifest = class Manifest {
 		}
 		this.webRoot = webRoot = resolvePath(webRoot || "./", referenceDir,
 				{ enforceRelative: true });
+		this.baseURI = baseURI || "/";
 
 		if(target) {
 			this.filepath = resolvePath(target, referenceDir, { enforceRelative: true });
@@ -27,8 +28,7 @@ exports.Manifest = class Manifest {
 		if(value) {
 			this.valueTransform = value;
 		} else {
-			baseURI = baseURI || "/";
-			this.valueTransform = filepath => baseURI + path.relative(webRoot, filepath);
+			this.valueTransform = filepath => this.baseURI + path.relative(webRoot, filepath);
 		}
 	}