diff --git a/_pytest/core.py b/_pytest/core.py
index e7a441634..04752dd71 100644
--- a/_pytest/core.py
+++ b/_pytest/core.py
@@ -68,7 +68,7 @@ class TagTracerSub:
         return self.__class__(self.root, self.tags + (name,))
 
 class PluginManager(object):
-    def __init__(self, hookspecs=None):
+    def __init__(self, hookspecs=None, prefix="pytest_"):
         self._name2plugin = {}
         self._listattrcache = {}
         self._plugins = []
@@ -77,7 +77,7 @@ class PluginManager(object):
         self.trace = TagTracer().get("pluginmanage")
         self._plugin_distinfo = []
         self._shutdown = []
-        self.hook = HookRelay(hookspecs or [], pm=self)
+        self.hook = HookRelay(hookspecs or [], pm=self, prefix=prefix)
 
     def do_configure(self, config):
         # backward compatibility
@@ -384,22 +384,25 @@ class HookRelay:
         self._hookspecs = []
         self._pm = pm
         self.trace = pm.trace.root.get("hook")
+        self.prefix = prefix
         for hookspec in hookspecs:
             self._addhooks(hookspec, prefix)
 
-    def _addhooks(self, hookspecs, prefix):
-        self._hookspecs.append(hookspecs)
+    def _addhooks(self, hookspec, prefix):
+        self._hookspecs.append(hookspec)
         added = False
-        for name, method in vars(hookspecs).items():
+        for name in dir(hookspec):
             if name.startswith(prefix):
+                method = getattr(hookspec, name)
                 firstresult = getattr(method, 'firstresult', False)
-                hc = HookCaller(self, name, firstresult=firstresult)
+                hc = HookCaller(self, name, firstresult=firstresult,
+                                argnames=varnames(method))
                 setattr(self, name, hc)
                 added = True
                 #print ("setting new hook", name)
         if not added:
             raise ValueError("did not find new %r hooks in %r" %(
-                prefix, hookspecs,))
+                prefix, hookspec,))
 
     def _getcaller(self, name, plugins):
         caller = getattr(self, name)
@@ -409,62 +412,44 @@ class HookRelay:
         return caller
 
     def _scan_plugin(self, plugin):
-        methods = collectattr(plugin)
-        hooks = {}
-        for hookspec in self._hookspecs:
-            hooks.update(collectattr(hookspec))
+        def fail(msg, *args):
+            name = getattr(plugin, '__name__', plugin)
+            raise PluginValidationError("plugin %r\n%s" %(name, msg % args))
 
-        stringio = py.io.TextIO()
-        def Print(*args):
-            if args:
-                stringio.write(" ".join(map(str, args)))
-            stringio.write("\n")
-
-        fail = False
-        while methods:
-            name, method = methods.popitem()
-            #print "checking", name
-            if isgenerichook(name):
+        for name in dir(plugin):
+            if not name.startswith(self.prefix):
                 continue
-            if name not in hooks:
-                if not getattr(method, 'optionalhook', False):
-                    Print("found unknown hook:", name)
-                    fail = True
-            else:
-                #print "checking", method
-                method_args = list(varnames(method))
-                if '__multicall__' in method_args:
-                    method_args.remove('__multicall__')
-                hook = hooks[name]
-                hookargs = varnames(hook)
-                for arg in method_args:
-                    if arg not in hookargs:
-                        Print("argument %r not available"  %(arg, ))
-                        Print("actual definition: %s" %(formatdef(method)))
-                        Print("available hook arguments: %s" %
-                                ", ".join(hookargs))
-                        fail = True
-                        break
-                #if not fail:
-                #    print "matching hook:", formatdef(method)
-                getattr(self, name).clear_method_cache()
-
-            if fail:
-                name = getattr(plugin, '__name__', plugin)
-                raise PluginValidationError("%s:\n%s" % (name, stringio.getvalue()))
+            hook = getattr(self, name, None)
+            method = getattr(plugin, name)
+            if hook is None:
+                is_optional = getattr(method, 'optionalhook', False)
+                if not isgenerichook(name) and not is_optional:
+                    fail("found unknown hook: %r", name)
+                continue
+            for arg in varnames(method):
+                if arg not in hook.argnames:
+                    fail("argument %r not available\n"
+                         "actual definition: %s\n"
+                         "available hookargs: %s",
+                         arg, formatdef(method),
+                           ", ".join(hook.argnames))
+            getattr(self, name).clear_method_cache()
 
 
 class HookCaller:
-    def __init__(self, hookrelay, name, firstresult, methods=None):
+    def __init__(self, hookrelay, name, firstresult, argnames, methods=None):
         self.hookrelay = hookrelay
         self.name = name
         self.firstresult = firstresult
         self.trace = self.hookrelay.trace
         self.methods = methods
+        self.argnames = ["__multicall__"]
+        self.argnames.extend(argnames)
+        assert "self" not in argnames
 
     def new_cached_caller(self, methods):
         return HookCaller(self.hookrelay, self.name, self.firstresult,
-                          methods=methods)
+                          argnames=self.argnames, methods=methods)
 
     def __repr__(self):
         return "<HookCaller %r>" %(self.name,)
@@ -474,14 +459,13 @@ class HookCaller:
 
     def __call__(self, **kwargs):
         methods = self.methods
-        if self.methods is None:
+        if methods is None:
             self.methods = methods = self.hookrelay._pm.listattr(self.name)
-            methods = self.methods
         return self._docall(methods, kwargs)
 
     def callextra(self, methods, **kwargs):
-        if self.methods is None:
-            self.reload_methods()
+        #if self.methods is None:
+        #    self.reload_methods()
         return self._docall(self.methods + methods, kwargs)
 
     def _docall(self, methods, kwargs):
diff --git a/testing/test_core.py b/testing/test_core.py
index e04720bb5..018532cc2 100644
--- a/testing/test_core.py
+++ b/testing/test_core.py
@@ -630,6 +630,18 @@ class TestHookRelay:
         assert l == [4]
         assert not hasattr(mcm, 'world')
 
+    def test_argmismatch(self):
+        class Api:
+            def hello(self, arg):
+                "api hook 1"
+        pm = PluginManager(Api, prefix="he")
+        class Plugin:
+            def hello(self, argwrong):
+                return arg + 1
+        with pytest.raises(PluginValidationError) as exc:
+            pm.register(Plugin())
+        assert "argwrong" in str(exc.value)
+
     def test_only_kwargs(self):
         pm = PluginManager()
         class Api: