diff --git a/R/parseBoolean.R b/R/parseBoolean.R
index 77c52c012ddc82ff0c07616abc1833503ba32abb..653aecc2e37b9de4f45c91a9fc7737693cdc3eb8 100644
--- a/R/parseBoolean.R
+++ b/R/parseBoolean.R
@@ -29,10 +29,11 @@
 # The function .parseBoolean() is inspired by the function
 # parseBoolean() contained in the COBRA Toolbox.
 # The algorithm is the same.
+#
+# 2015-06-17 CJF: added handling for emtpy gprRule like "( )"
 
 
 .parseBoolean <- function(gprRule, tokens = "()&|~") {
-	print(gprRule)
 
 #.parseBoolean <- function(gprRule,
 #                          tokens = "()&|~",