diff -r 06d196031fa1 src/org/python/core/Py.java
--- a/src/org/python/core/Py.java	Wed Jun 25 17:44:39 2014 -0600
+++ b/src/org/python/core/Py.java	Thu Jun 26 15:49:37 2014 -0600
@@ -882,7 +882,6 @@
         }
         return loadAndInitClass(name, Thread.currentThread().getContextClassLoader());
     }
-    
     /**
      * Tries to find a Java class.
      * @param name Name of the Java class.
diff -r 06d196031fa1 src/org/python/core/PyBaseCode.java
--- a/src/org/python/core/PyBaseCode.java	Wed Jun 25 17:44:39 2014 -0600
+++ b/src/org/python/core/PyBaseCode.java	Thu Jun 26 15:49:37 2014 -0600
@@ -64,7 +64,7 @@
         }
 
         PyObject ret;
-        ThreadStateMapping.enterCall(ts);
+        ClassLoader previous_classloader = ThreadStateMapping.enterCall(ts);
         try {
             ret = interpret(frame, ts);
         } catch (Throwable t) {
@@ -86,7 +86,7 @@
             ts.frame = ts.frame.f_back;
             throw pye;
         } finally {
-            ThreadStateMapping.exitCall(ts);
+            ThreadStateMapping.exitCall(ts, previous_classloader);
         }
 
         if (frame.tracefunc != null) {
diff -r 06d196031fa1 src/org/python/core/PyTableCode.java
--- a/src/org/python/core/PyTableCode.java	Wed Jun 25 17:44:39 2014 -0600
+++ b/src/org/python/core/PyTableCode.java	Thu Jun 26 15:49:37 2014 -0600
@@ -161,7 +161,7 @@
         }
 
         PyObject ret;
-        ThreadStateMapping.enterCall(ts);
+        ClassLoader previous_classloader = ThreadStateMapping.enterCall(ts);
         try {
             ret = funcs.call_function(func_id, frame, ts);
         } catch (Throwable t) {
@@ -183,7 +183,7 @@
             ts.frame = ts.frame.f_back;
             throw pye;
         } finally {
-            ThreadStateMapping.exitCall(ts);
+            ThreadStateMapping.exitCall(ts, previous_classloader);
         }
 
         if (frame.tracefunc != null) {
diff -r 06d196031fa1 src/org/python/core/ThreadStateMapping.java
--- a/src/org/python/core/ThreadStateMapping.java	Wed Jun 25 17:44:39 2014 -0600
+++ b/src/org/python/core/ThreadStateMapping.java	Thu Jun 26 15:49:37 2014 -0600
@@ -39,21 +39,34 @@
         return ts;
     }
 
-    public static void enterCall(ThreadState ts) {
+    public static ClassLoader enterCall(ThreadState ts) {
+        ClassLoader previous = null;
         if (ts.call_depth == 0) {
             scopedThreadState.get()[0] = ts;
-//            Thread.currentThread().setContextClassLoader(imp.getSyspathJavaLoader());
+            previous = Thread.currentThread().getContextClassLoader();
+            if (previous != null)
+            try {
+                Thread.currentThread().setContextClassLoader(imp.getSyspathJavaLoader());
+            } catch (SecurityException e) {
+            }
         } else if (ts.call_depth > ts.systemState.getrecursionlimit()) {
             throw Py.RuntimeError("maximum recursion depth exceeded");
         }
         ts.call_depth++;
+        return previous;
     }
 
-    public static void exitCall(ThreadState ts) {
+    public static void exitCall(ThreadState ts, ClassLoader previous) {
         ts.call_depth--;
         if (ts.call_depth == 0) {
+            assert scopedThreadState.get()[0] == ts;
             scopedThreadState.get()[0] = null;
-//            Thread.currentThread().setContextClassLoader(null);
+            System.err.println(
+                    "contextClassLoader thread=" + Thread.currentThread() +
+                    ", previous=" + previous);
+            if (previous == null) {
+                Thread.currentThread().setContextClassLoader(previous);
+            }
         }
     }
 }