diff --git a/liberty/LibertyParse.yy b/liberty/LibertyParse.yy
index 98ff1360..50ac1d88 100644
--- a/liberty/LibertyParse.yy
+++ b/liberty/LibertyParse.yy
@@ -119,6 +119,9 @@ complex_attr:
 |	KEYWORD '(' attr_values ')' line semi_opt
 	{ $$ = sta::makeLibertyComplexAttr($1, $3, $5); }
 	;
+|	KEYWORD '(' colon_expr ')' line semi_opt
+	{ $$ = sta::makeLibertyComplexAttr($1, $3, $5); }
+	;
 
 attr_values:
 	attr_value
diff --git a/test/ccs_input_ccb_colon.lib b/test/ccs_input_ccb_colon.lib
index 2d419603..65a405a2 100644
--- a/test/ccs_input_ccb_colon.lib
+++ b/test/ccs_input_ccb_colon.lib
@@ -38,6 +38,7 @@ library (ccs_input_ccb_colon) {
       related_ground_pin : VSS ; 
       related_power_pin : VDD ; 
       rise_capacitance : 0.0001 ; 
+      active_input_ccb(ccs_input_ccb_colon:ck);
 
       input_ccb(ccs_input_ccb_colon:a) { 
         is_needed : true ;