diff --git a/src/ShadowCSS.js b/src/ShadowCSS.js
index a8dbfee..316fda6 100644
--- a/src/ShadowCSS.js
+++ b/src/ShadowCSS.js
@@ -518,15 +518,16 @@ var hostRuleRe = /@host[^{]*{(([^}]*?{[^{]*?}[\s\S]*?)+)}/gim,
     cssPolyfillUnscopedRuleCommentRe = /\/\*\s@polyfill-unscoped-rule([^*]*\*+([^/*][^*]*\*+)*)\//gim,
     cssPseudoRe = /::(x-[^\s{,(]*)/gim,
     cssPartRe = /::part\(([^)]*)\)/gim,
-    // note: :host pre-processed to -host.
-    cssColonHostRe = /(-host)(?:\(([^)]*)\))?([^,{]*)/gim,
+    // note: :host pre-processed to -shadowcsshost.
+    polyfillHost = '-shadowcsshost',
+    cssColonHostRe = new RegExp('(' + polyfillHost +
+        ')(?:\\(([^)]*)\\))?([^,{]*)', 'gim'),
     selectorReSuffix = '([>\\s~+\[.,{:][\\s\\S]*)?$',
     hostRe = /@host/gim,
     colonHostRe = /\:host/gim,
-    polyfillHost = '-host',
     /* host name without combinator */
-    polyfillHostNoCombinator = '-host-no-combinator',
-    polyfillHostRe = /-host/gim;
+    polyfillHostNoCombinator = polyfillHost + '-no-combinator',
+    polyfillHostRe = new RegExp(polyfillHost, 'gim');
 
 function stylesToCssText(styles, preserveComments) {
   var cssText = '';