diff --git a/src/xmlsec/constants.pxd b/src/xmlsec/constants.pxd
index b7aedefd..40a3d2b8 100644
--- a/src/xmlsec/constants.pxd
+++ b/src/xmlsec/constants.pxd
@@ -6,7 +6,6 @@ cdef extern from "xmlsec.h":  # xmlsec/strings.h
     const_xmlChar* xmlSecNs
     const_xmlChar* xmlSecDSigNs
     const_xmlChar* xmlSecEncNs
-    const_xmlChar* xmlSecXkmsNs
     const_xmlChar* xmlSecXPathNs
     const_xmlChar* xmlSecXPath2Ns
     const_xmlChar* xmlSecXPointerNs
diff --git a/src/xmlsec/constants.pyx b/src/xmlsec/constants.pyx
index 6d2eecf5..a6de7cd8 100644
--- a/src/xmlsec/constants.pyx
+++ b/src/xmlsec/constants.pyx
@@ -17,7 +17,6 @@ class Namespace:
     BASE = _u(xmlSecNs)
     DS = _u(xmlSecDSigNs)
     ENC = _u(xmlSecEncNs)
-    XKMS = _u(xmlSecXkmsNs)
     XPATH = _u(xmlSecXPathNs)
     XPATH2 = _u(xmlSecXPath2Ns)
     XPOINTER = _u(xmlSecXPointerNs)