diff --git a/lib/buildPermissionsPolicyHeaders.js b/lib/buildPermissionsPolicyHeaders.js
index e87b348..8cca9fc 100644
--- a/lib/buildPermissionsPolicyHeaders.js
+++ b/lib/buildPermissionsPolicyHeaders.js
@@ -4,14 +4,17 @@ const crunchPermissionsPolicyHeader = require('./crunchPermissionsPolicyHeader.j
 const directives = require('./PermissionsPolicy/index.js')
 
 
-function reduceDirectives (policy, defaultValue) {
-	return (accumulator, directive) => {
-		if (policy[directive] !== false) {
-			accumulator[directive] = policy[directive] || defaultValue
-		}
-
-		return accumulator
-	}
+function reduceDirectives (supportedDirectives, permissionsPolicy, defaultValue) {
+	return supportedDirectives.reduce(
+		(accumulator, directive) => {
+			if (permissionsPolicy[directive] !== false) {
+				accumulator[directive] = permissionsPolicy[directive] || defaultValue
+			}
+
+			return accumulator
+		},
+		{}
+	)
 }
 
 
@@ -25,19 +28,22 @@ module.exports = function buildPermissionsPolicyHeaders(options = {}) {
 		return []
 	}
 
-	const supportedDirectives = Array.from(new Set(permissionsPolicyDirectiveSupport
-		.map(directiveSet => directives[directiveSet])
-		.flat()))
-		
+	const supportedDirectives = Array.from(
+		new Set(
+			permissionsPolicyDirectiveSupport.map(
+				directiveSet => directives[directiveSet]
+			).flat()
+		)
+	)
+
 	return [
 		{
 			key: 'Feature-Policy',
-			value: crunchFeaturePolicyHeader(supportedDirectives.reduce(reduceDirectives(permissionsPolicy, "'none'"))),
+			value: crunchFeaturePolicyHeader(reduceDirectives(supportedDirectives, permissionsPolicy, "'none'"))
 		},
-
 		{
 			key: 'Permissions-Policy',
-			value: crunchPermissionsPolicyHeader(supportedDirectives.reduce(reduceDirectives(permissionsPolicy, ''))),
+			value: crunchPermissionsPolicyHeader(reduceDirectives(supportedDirectives, permissionsPolicy, '')),
 		},
 	]
 }