diff --git a/jpype/_jproxy.py b/jpype/_jproxy.py
index 2efa79df4..8c484cae7 100644
--- a/jpype/_jproxy.py
+++ b/jpype/_jproxy.py
@@ -59,6 +59,9 @@ def _createJProxyDeferred(cls, *intf):
     @JOverride notation on methods evaluated at first
     instantiation.
     """
+    if not isinstance(cls, type):
+        raise TypeError("JImplements only applies to types, not %s" % (type(cls)))
+
     def new(tp, *args, **kwargs):
         # Attach a __jpype_interfaces__ attribute to this class if
         # one doesn't already exist.
@@ -77,6 +80,9 @@ def _createJProxy(cls, *intf):
     """ (internal) Create a proxy from a Python class with
     @JOverride notation on methods evaluated at declaration.
     """
+    if not isinstance(cls, type):
+        raise TypeError("JImplements only applies to types, not %s" % (type(cls)))
+
     actualIntf = _prepareInterfaces(cls, intf)
 
     def new(tp, *args, **kwargs):
diff --git a/test/jpypetest/test_proxy.py b/test/jpypetest/test_proxy.py
index 8cba2006e..0cba57b52 100644
--- a/test/jpypetest/test_proxy.py
+++ b/test/jpypetest/test_proxy.py
@@ -138,6 +138,7 @@ def testMethod1(self):
     def testProxyImplementsForm2(self):
         itf1 = self.package.TestInterface1
         itf2 = self.package.TestInterface2
+
         @JImplements(itf1, itf2)
         class MyImpl(object):
             @JOverride
@@ -392,6 +393,7 @@ def equals(self, _obj):
 
     def testUnwrap(self):
         fixture = JClass("jpype.common.Fixture")()
+
         @JImplements("java.io.Serializable")
         class Q(object):
             pass
@@ -429,6 +431,7 @@ class R(object):
 
     def testMethods(self):
         fixture = JClass("jpype.common.Fixture")()
+
         @JImplements("java.io.Serializable")
         class R(object):
             pass
@@ -472,6 +475,7 @@ def run(self):
 
     def testWeak(self):
         hc = java.lang.System.identityHashCode
+
         @JImplements("java.io.Serializable")
         class MyObj(object):
             pass
@@ -496,6 +500,14 @@ def testFunctionalLambda(self):
         js = JObject(lambda x: 2 * x, "java.util.function.DoubleUnaryOperator")
         self.assertEqual(js.applyAsDouble(1), 2.0)
 
+    def testBadImplements(self):
+        with self.assertRaises(TypeError):
+            @JImplements("java.lang.Runnable")
+            def MyImpl(object):
+                @JOverride
+                def run(self):
+                    pass
+
 
 @subrun.TestCase(individual=True)
 class TestProxyDefinitionWithoutJVM(common.JPypeTestCase):