diff --git a/NAMESPACE b/NAMESPACE
index 40187aa..c9ab0ff 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -20,6 +20,7 @@ import(ergm)
 import(network)
 import(statnet.common)
 import(stats)
+importFrom(utils,packageVersion)
 importFrom(stats,as.formula)
 importFrom(stats,var)
 useDynLib(ergm.tapered)
diff --git a/R/zzz.R b/R/zzz.R
index 2f4a93c..25c5aa8 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -5,8 +5,8 @@
 .onLoad <- function(libname, pkgname){
   utils::globalVariables(names=c(".","NO_LOGLIK_MESSAGE","NO_NULL_IMPLICATION"))
   .RegisterKeywords()
-  if(packageVersion("ergm") != "4.3.6983"){
-    stop("ergm.tapered requires a variant of the current version of 'ergm' (the 'tapered' branch).\n To install it use:\n devtools::install_github('statnet/ergm', ref='tapered')")
+  if(utils::packageVersion("ergm") != "4.3.6983"){
+    stop("ergm.tapered requires a variant of the current version of 'ergm' (the 'tapered' branch).\n  To install it use:\n devtools::install_github('statnet/ergm', ref='tapered')")
   }
 }