diff --git a/R/init.R b/R/init.R
index 4c4c4488..b9d4c750 100644
--- a/R/init.R
+++ b/R/init.R
@@ -25,7 +25,5 @@ NULL
 }
 
 .onUnload = function(libname, pkgname) {
-  # force run weak finalizers before freeing sys
-  invisible(gc())
 	udunits_exit()
 }
diff --git a/src/udunits.cpp b/src/udunits.cpp
index ac980e82..58b0ae1d 100644
--- a/src/udunits.cpp
+++ b/src/udunits.cpp
@@ -30,10 +30,17 @@ typedef XPtr<ut_unit, PreserveStorage, ut_free, true> XPtrUT;
 static ut_system *sys = NULL;
 static ut_encoding enc = UT_UTF8;
 
+// [[Rcpp::export]]
+void udunits_exit() {
+  R_gc();
+  ut_free_system(sys);
+  sys = NULL;
+}
+
 // [[Rcpp::export]]
 void udunits_init(CharacterVector path) {
   ut_set_error_message_handler(ut_ignore);
-  ut_free_system(sys);
+  udunits_exit();
   for (int i = 0; i < path.size(); i++) {
     if ((sys = ut_read_xml(path[i])) != NULL)
       break;
@@ -45,12 +52,6 @@ void udunits_init(CharacterVector path) {
     stop("no database found!"); // #nocov
 }
 
-// [[Rcpp::export]]
-void udunits_exit() {  // #nocov start
-  ut_free_system(sys);
-  sys = NULL;
-}                      // #nocov end
-
 // wrap a ut_unit pointer in an XPtr
 SEXP ut_wrap(ut_unit *u) {
   XPtrUT p(u);