diff --git a/DynamicLoader.cxx b/DynamicLoader.cxx
index 66c7d576754ae1badb56b697992d76061ae2fa7c..a776f97b0072ff39df98debf820f01bce1046cf2 100644
--- a/DynamicLoader.cxx
+++ b/DynamicLoader.cxx
@@ -48,6 +48,10 @@ DynamicLoader::LibraryHandle DynamicLoader::OpenLibrary(const kwsys_stl::string&
 //----------------------------------------------------------------------------
 int DynamicLoader::CloseLibrary(DynamicLoader::LibraryHandle lib)
 {
+  if (!lib)
+    {
+    return 0;
+    }
   return !shl_unload(lib);
 }