diff --git a/IPython/frontend/cocoa/cocoa_frontend.py b/IPython/frontend/cocoa/cocoa_frontend.py
index 9f9aa55..63c7947 100644
--- a/IPython/frontend/cocoa/cocoa_frontend.py
+++ b/IPython/frontend/cocoa/cocoa_frontend.py
@@ -288,9 +288,13 @@ class IPythonCocoaController(NSObject, FrontEndBase):
     def current_indent_string(self):
         """returns string for indent or None if no indent"""
         
-        if(len(self.current_block()) > 0):
-            lines = self.current_block().split('\n')
-            currentIndent = len(lines[-1]) - len(lines[-1])
+        return self._indent_for_block(self.currentBlock())
+    
+    
+    def _indent_for_block(self, block):
+        lines = block.split('\n')
+        if(len(lines) > 1):
+            currentIndent = len(lines[-1]) - len(lines[-1].lstrip())
             if(currentIndent == 0):
                 currentIndent = self.tabSpaces
         
diff --git a/IPython/frontend/cocoa/tests/test_cocoa_frontend.py b/IPython/frontend/cocoa/tests/test_cocoa_frontend.py
index eb4ae43..d85728d 100644
--- a/IPython/frontend/cocoa/tests/test_cocoa_frontend.py
+++ b/IPython/frontend/cocoa/tests/test_cocoa_frontend.py
@@ -70,3 +70,22 @@ class TestIPythonCocoaControler(DeferredTestCase):
         
         self.controller.execute(code).addCallback(testCompletes)
     
+    
+    def testCurrentIndent(self):
+        """test that current_indent_string returns current indent or None.
+        Uses _indent_for_block for direct unit testing.
+        """
+        
+        self.controller.tabUsesSpaces = True
+        self.assert_(self.controller._indent_for_block("""a=3""") == None)
+        self.assert_(self.controller._indent_for_block("") == None)
+        block = """def test():\n    a=3"""
+        self.assert_(self.controller._indent_for_block(block) == \
+                    ' ' * self.controller.tabSpaces)
+        
+        block = """if(True):\n%sif(False):\n%spass""" % \
+                    (' '*self.controller.tabSpaces,
+                     2*' '*self.controller.tabSpaces)
+        self.assert_(self.controller._indent_for_block(block) == \
+                    2*(' '*self.controller.tabSpaces))
+