diff --git a/src/CustomElements/CustomElements.js b/src/CustomElements/CustomElements.js
index 8ef94e6..14d33c6 100644
--- a/src/CustomElements/CustomElements.js
+++ b/src/CustomElements/CustomElements.js
@@ -18,7 +18,10 @@ var flags = {};
 if (!flags.noOpts) {
   location.search.slice(1).split('&').forEach(function(o) {
     o = o.split('=');
-    o[0] && (flags[o[0]] = o[1] || true);
+    var m;
+    if (o[0] && (m = o[0].match(/wc-(.+)/))) {
+      flags[m[1]] = o[1] || true;
+    }
   });
 }
 
diff --git a/src/HTMLImports/HTMLImports.js b/src/HTMLImports/HTMLImports.js
index 2b76f5d..e357f1f 100644
--- a/src/HTMLImports/HTMLImports.js
+++ b/src/HTMLImports/HTMLImports.js
@@ -18,7 +18,10 @@ var flags = {};
 if (!flags.noOpts) {
   location.search.slice(1).split('&').forEach(function(o) {
     o = o.split('=');
-    o[0] && (flags[o[0]] = o[1] || true);
+    var m;
+    if (o[0] && (m = o[0].match(/wc-(.+)/))) {
+      flags[m[1]] = o[1] || true;
+    }
   });
 }
 
diff --git a/src/WebComponents/build/boot-lite.js b/src/WebComponents/build/boot-lite.js
index 4c3a6f4..f78eb7e 100644
--- a/src/WebComponents/build/boot-lite.js
+++ b/src/WebComponents/build/boot-lite.js
@@ -11,10 +11,10 @@ window.WebComponents = window.WebComponents || {};
 
 // process flags
 (function(scope){
-  
+
   // import
   var flags = scope.flags || {};
-  
+
   var file = 'webcomponents-lite.js';
   var script = document.querySelector('script[src*="' + file + '"]');
 
@@ -23,7 +23,10 @@ window.WebComponents = window.WebComponents || {};
     // from url
     location.search.slice(1).split('&').forEach(function(o) {
       o = o.split('=');
-      o[0] && (flags[o[0]] = o[1] || true);
+      var m;
+      if (o[0] && (m = o[0].match(/wc-(.+)/))) {
+        flags[m[1]] = o[1] || true;
+      }
     });
     // from script
     if (script) {
@@ -48,7 +51,7 @@ window.WebComponents = window.WebComponents || {};
   // Determine default settings.
   // If any of these flags match 'native', then force native ShadowDOM; any
   // other truthy value, or failure to detect native
-  // ShadowDOM, results in polyfill 
+  // ShadowDOM, results in polyfill
   flags.shadow = (flags.shadow || flags.shadowdom || flags.polyfill);
   if (flags.shadow === 'native') {
     flags.shadow = false;
diff --git a/src/WebComponents/build/boot.js b/src/WebComponents/build/boot.js
index 54c662f..c7164ea 100644
--- a/src/WebComponents/build/boot.js
+++ b/src/WebComponents/build/boot.js
@@ -23,7 +23,10 @@ window.WebComponents = window.WebComponents || {};
     // from url
     location.search.slice(1).split('&').forEach(function(o) {
       o = o.split('=');
-      o[0] && (flags[o[0]] = o[1] || true);
+      var m;
+      if (o[0] && (m = o[0].match(/wc-(.+)/))) {
+        flags[m[1]] = o[1] || true;
+      }
     });
     // from script
     if (script) {
diff --git a/webcomponents-lite.js b/webcomponents-lite.js
index b7a8d29..08034ca 100644
--- a/webcomponents-lite.js
+++ b/webcomponents-lite.js
@@ -23,7 +23,10 @@
     // from url
     location.search.slice(1).split('&').forEach(function(o) {
       o = o.split('=');
-      o[0] && (flags[o[0]] = o[1] || true);
+      var m;
+      if (o[0] && (m = o[0].match(/wc-(.+)/))) {
+        flags[m[1]] = o[1] || true;
+      }
     });
     // from script
     if (script) {
diff --git a/webcomponents.js b/webcomponents.js
index 8112c73..4c632f7 100644
--- a/webcomponents.js
+++ b/webcomponents.js
@@ -23,7 +23,10 @@
     // from url
     location.search.slice(1).split('&').forEach(function(o) {
       o = o.split('=');
-      o[0] && (flags[o[0]] = o[1] || true);
+      var m;
+      if (o[0] && (m = o[0].match(/wc-(.+)/))) {
+        flags[m[1]] = o[1] || true;
+      }
     });
     // from script
     if (script) {