diff --git a/sumpy/kernel.py b/sumpy/kernel.py
index e1e8c6717269edb4d2ffb7e88a694b541ab76a18..becc99c015af6b99df5ecd9b1a223830d2761034 100644
--- a/sumpy/kernel.py
+++ b/sumpy/kernel.py
@@ -244,7 +244,8 @@ class ExpressionKernel(Kernel):
         self.is_complex_valued = is_complex_valued
 
     def __getinitargs__(self):
-        return (self._dim,)
+        return (self._dim, self.expression, self.scaling,
+                self.is_complex_valued)
 
     def __repr__(self):
         if self._dim is not None:
@@ -282,6 +283,16 @@ class ExpressionKernel(Kernel):
         from sumpy.symbolic import PymbolicToSympyMapperWithSymbols
         return PymbolicToSympyMapperWithSymbols()(self.scaling)
 
+    def update_persistent_hash(self, key_hash, key_builder):
+        key_hash.update(type(self).__name__.encode("utf8"))
+        for name, value in zip(self.init_arg_names, self.__getinitargs__()):
+            if name in ["expression", "scaling"]:
+                from pymbolic.mapper.persistent_hash import (
+                        PersistentHashWalkMapper as PersistentHashWalkMapper)
+                PersistentHashWalkMapper(key_hash)(value)
+            else:
+                key_builder.rec(key_hash, value)
+
     mapper_method = "map_expression_kernel"
 
 
diff --git a/sumpy/version.py b/sumpy/version.py
index 5cc1934ddcfbfd8b5e3925d887d5f6f321aa4447..a19f3ddac1540cf069923ed59355c57387c7a5a7 100644
--- a/sumpy/version.py
+++ b/sumpy/version.py
@@ -25,4 +25,4 @@ VERSION = (2016, 1)
 VERSION_STATUS = "beta1"
 VERSION_TEXT = ".".join(str(x) for x in VERSION) + VERSION_STATUS
 
-KERNEL_VERSION = 7
+KERNEL_VERSION = 8