diff --git a/DESCRIPTION b/DESCRIPTION
index f31336a01503bc6b8eed349b22ff4400843a53dc..e0b94d903027e184870c7585d25c7b3fec78f489 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,8 +1,8 @@
 Package: sybil
 Type: Package
 Title: Efficient Constrained Based Modelling in R
-Version: 2.0.0
-Date: 2016-05-12
+Version: 2.0.1
+Date: 2016-05-25
 Authors@R: c(
 	     person(c("C.", "Jonathan"), "Fritzemeier", role = c("cre", "ctb"), email = "clausjonathan.fritzemeier@uni-duesseldorf.de"),
 	     person("Gabriel", "Gelius-Dietrich", role = c("aut")),
@@ -53,7 +53,7 @@ Collate: generics.R validmodelorg.R validoptsol.R validreactId.R
         sysBiolAlg_lmomaClass.R sysBiolAlg_momaClass.R
         sysBiolAlg_mtfClass.R sysBiolAlg_mtfEasyConstraintClass.R
         sysBiolAlg_roomClass.R sybilLogClass.R upgradeModelorg.R
-Packaged: 2016-05-12 12:34:14 UTC; jonathan
+Packaged: 2016-05-25 12:34:14 UTC; jonathan
 Author: C. Jonathan Fritzemeier [cre, ctb],
   Gabriel Gelius-Dietrich [aut],
   Rajen Piernikarczyk [ctb],
diff --git a/R/upgradeModelorg.R b/R/upgradeModelorg.R
index a10cdfd16b9025d30aa34c9a5da0c8c0b81c0ba9..809c1c811a53cabd2919c5ed4aff120ea812d78c 100644
--- a/R/upgradeModelorg.R
+++ b/R/upgradeModelorg.R
@@ -41,8 +41,14 @@ upgradeModelorg <- function(object){
 		
 		# update gprRules to new format
 		rules <- lapply(gpr(object), .parseBoolean)
-		genes(object) <- sapply(rules, "[[", "gene")
-		gprRules(object) <- sapply(rules, "[[", "rule")
+		if(length(rules) == 0){
+			genes(object) <- list()
+			gprRules(object) <- character(0)
+		}else{
+			genes(object) <- lapply(rules, "[[", "gene")
+			gprRules(object) <- sapply(rules, "[[", "rule")
+		}
+		
 		
 		# set attribute slots
 		react_attr(object) <- data.frame()
diff --git a/inst/NEWS.Rd b/inst/NEWS.Rd
index 37e5130676796860925a542bc8a58b681962cf60..9f9fd1fc7e00edb4df6c915bc1bf7afc4e1e3aeb 100644
--- a/inst/NEWS.Rd
+++ b/inst/NEWS.Rd
@@ -6,6 +6,13 @@
 
 \newcommand{\CRANpkg}{\href{http://CRAN.R-project.org/package=#1}{\pkg{#1}}}
 
+\section{Changes in version 2.0.1 2016-07-05}{
+  \itemize{
+  	\item \code{upgradeModelorg} was not working correctly, when all gprRules
+  	are empty.
+  }
+}
+% ---------------------------------------------------------------------------- %
 \section{Changes in version 2.0.0 2016-05-17}{
   \itemize{
   	\item \code{modelorg}-class has changed and thus a slot \code{version} was introduced.