Index: zc.recipe.egg_/src/zc/recipe/egg/custom.py
===================================================================
--- zc.recipe.egg_/src/zc/recipe/egg/custom.py	(revision 102361)
+++ zc.recipe.egg_/src/zc/recipe/egg/custom.py	(working copy)
@@ -31,7 +31,14 @@
 
         python = options.get('python', buildout['buildout']['python'])
         options['executable'] = buildout[python]['executable']
+        if not os.path.isfile(options['executable']):
+            raise zc.buildout.UserError(
+                    'The specified python executable :\n'
+                    '%r\n'
+                    "Doesn't exist.\n"
+                    % options['executable'])
 
+
         self.build_ext = build_ext(buildout, options)
 
     def update(self):
Index: zc.recipe.egg_/src/zc/recipe/egg/egg.py
===================================================================
--- zc.recipe.egg_/src/zc/recipe/egg/egg.py	(revision 102361)
+++ zc.recipe.egg_/src/zc/recipe/egg/egg.py	(working copy)
@@ -54,7 +54,14 @@
 
         python = options.get('python', buildout['buildout']['python'])
         options['executable'] = buildout[python]['executable']
+        if not os.path.isfile(options['executable']):
+            raise zc.buildout.UserError(
+                    'The specified python executable :\n'
+                    '%r\n'
+                    "Doesn't exist.\n"
+                    % options['executable'])
 
+
     def working_set(self, extra=()):
         """Separate method to just get the working set