Index: src/main/groovy/lang/GroovyClassLoader.java
===================================================================
--- src/main/groovy/lang/GroovyClassLoader.java	(revision 4380)
+++ src/main/groovy/lang/GroovyClassLoader.java	(working copy)
@@ -313,7 +313,8 @@
                 if (shouldCacheSource) sourceCache.put(codeSource.getName(), answer);
             } finally {
                 try {
-                    codeSource.getInputStream().close();
+                    InputStream is = codeSource.getInputStream(); 
+                    if(is != null) is.close();
                 } catch (IOException e) {
                     throw new GroovyRuntimeException("unable to close stream",e);
                 }