diff --git a/build.xml b/build.xml
index dc1f7fa5..577663f9 100644
--- a/build.xml
+++ b/build.xml
@@ -654,13 +654,16 @@
                     <arg value="@{digest}"/>
 
                     <!--
-                        If we have a PKCS11 configuration specified, include it.
+                        If we have a PKCS#11 configuration specified, include it.
                     -->
                     <arg if:set="keystore.pkcs11.config" value="--pkcs11Config"/>
                     <arg if:set="keystore.pkcs11.config" value="${keystore.pkcs11.config}"/>
 
-                    <arg value="--keystoreProvider"/>
-                    <arg value="sun.security.pkcs11.SunPKCS11"/>
+                    <!--
+                        If we have a non-default keystore provider specified, include it.
+                    -->
+                    <arg if:set="keystore.uk.sign.provider" value="--keystoreProvider"/>
+                    <arg if:set="keystore.uk.sign.provider" value="${keystore.uk.sign.provider}"/>
 
                     <arg value="--key"/>
                     <arg value="${keystore.uk.sign.alias}"/>
diff --git a/preprod.properties b/preprod.properties
index e5e5048c..f9a06990 100644
--- a/preprod.properties
+++ b/preprod.properties
@@ -4,6 +4,11 @@
 # Properties defined for the env=preprod deployment environment.
 #
 
+#
+# Use the PKCS#11 provider for signatures.
+#
+keystore.uk.sign.provider = sun.security.pkcs11.SunPKCS11
+
 #
 # Location of the PKCS#11 configuration file for the Thales HSM.
 #
diff --git a/prod-old.properties b/prod-old.properties
index 4d51bc90..a7269a06 100644
--- a/prod-old.properties
+++ b/prod-old.properties
@@ -7,6 +7,11 @@
 # to be used again in anger.
 #
 
+#
+# Use the PKCS#11 provider for signatures.
+#
+keystore.uk.sign.provider = sun.security.pkcs11.SunPKCS11
+
 #
 # Location of the PKCS#11 configuration file for an ACOS5 card.
 #
diff --git a/prod.properties b/prod.properties
index ec8bc5a6..26764173 100644
--- a/prod.properties
+++ b/prod.properties
@@ -4,6 +4,11 @@
 # Properties defined for the env=prod deployment environment.
 #
 
+#
+# Use the PKCS#11 provider for signatures.
+#
+keystore.uk.sign.provider = sun.security.pkcs11.SunPKCS11
+
 #
 # Location of the PKCS#11 configuration file for the Thales HSM.
 #