diff --git a/basis/alien/libraries/libraries-tests.factor b/basis/alien/libraries/libraries-tests.factor
new file mode 100644
index 0000000000..13eb134ea9
--- /dev/null
+++ b/basis/alien/libraries/libraries-tests.factor
@@ -0,0 +1,10 @@
+IN: alien.libraries.tests
+USING: alien.libraries alien.syntax tools.test kernel ;
+
+[ f ] [ DLL" fadfasdfsada" dll-valid? ] unit-test
+
+[ f ] [ "does not exist" DLL" fadsfasfdsaf" dlsym ] unit-test
+
+[ ] [ "doesnotexist" dlopen dlclose ] unit-test
+
+[ "fdasfsf" dll-valid? drop ] must-fail
\ No newline at end of file
diff --git a/core/alien/alien-tests.factor b/core/alien/alien-tests.factor
index d3265f31bb..2d2cec168f 100644
--- a/core/alien/alien-tests.factor
+++ b/core/alien/alien-tests.factor
@@ -71,10 +71,6 @@ cell 8 = [
 
 [ "( displaced alien )" ] [ 0 B{ 1 2 3 } <displaced-alien> unparse ] unit-test
 
-[ f ] [ DLL" fadfasdfsada" dll-valid? ] unit-test
-
-[ f ] [ "does not exist" DLL" fadsfasfdsaf" dlsym ] unit-test
-
 SYMBOL: initialize-test
 
 f initialize-test set-global
diff --git a/vm/alien.cpp b/vm/alien.cpp
index 49afd608ec..13764a8e50 100755
--- a/vm/alien.cpp
+++ b/vm/alien.cpp
@@ -134,20 +134,21 @@ PRIMITIVE(dlsym)
 		box_alien(ffi_dlsym(NULL,sym));
 	else
 	{
-		tagged<dll> d = library.as<dll>();
-		d.untag_check();
+		dll *d = untag_check<dll>(library.value());
 
 		if(d->dll == NULL)
 			dpush(F);
 		else
-			box_alien(ffi_dlsym(d.untagged(),sym));
+			box_alien(ffi_dlsym(d,sym));
 	}
 }
 
 /* close a native library handle */
 PRIMITIVE(dlclose)
 {
-	ffi_dlclose(untag_check<dll>(dpop()));
+	dll *d = untag_check<dll>(dpop());
+	if(d->dll != NULL)
+		ffi_dlclose(d);
 }
 
 PRIMITIVE(dll_validp)
@@ -156,7 +157,7 @@ PRIMITIVE(dll_validp)
 	if(library == F)
 		dpush(T);
 	else
-		dpush(tagged<dll>(library)->dll == NULL ? F : T);
+		dpush(untag_check<dll>(library)->dll == NULL ? F : T);
 }
 
 /* gets the address of an object representing a C pointer */