diff --git a/lib/style-ast.js b/lib/style-ast.js
index fb2db7a..cb63d5d 100644
--- a/lib/style-ast.js
+++ b/lib/style-ast.js
@@ -171,9 +171,9 @@ class StyleAST {
 				}
 
 				// Make all global colors and global typographies with only one digit be available.
-				let awbColorWithSingleDigit = '(color|custom_color_\d(\D|$))';
-				let awbTypoWithSingleDigit  = '(typography|custom_typography_\d(\D|$))';
-				let colorOrTypoVars = new RegExp( '--awb-(' + awbColorWithSingleDigit + '|' + awbTypoWithSingleDigit + ')' );
+				const colorOrTypoVars = new RegExp(
+					/--awb-((color|custom_color_\d(\D|$))|(typography|custom_typography_\d(\D|$)))/
+				);
 				if ( colorOrTypoVars.test( declaration.property ) ) {
 					return;
 				}