diff --git a/pytential/qbx/direct.py b/pytential/qbx/direct.py
index 70fa0d1a9e4bbdc6b01a00ca66ab4bc1ce22ab5a..7ad1782c7478f1d6394a613e1542fe1aaa799d31 100644
--- a/pytential/qbx/direct.py
+++ b/pytential/qbx/direct.py
@@ -27,12 +27,18 @@ import numpy as np
 
 from sumpy.qbx import LayerPotentialBase
 
+from pytential.version import PYTENTIAL_KERNEL_VERSION
+
 
 # {{{ qbx applier on a target/center subset
 
 class LayerPotentialOnTargetAndCenterSubset(LayerPotentialBase):
     default_name = "qbx_tgt_ctr_subset"
 
+    def get_cache_key(self):
+        return super(LayerPotentialOnTargetAndCenterSubset, self).get_cache_key() + (
+                PYTENTIAL_KERNEL_VERSION,)
+
     def get_kernel(self):
         loopy_insns, result_names = self.get_loopy_insns_and_result_names()
         kernel_exprs = self.get_kernel_exprs(result_names)