diff --git a/src/AlfClient.h b/src/AlfClient.h
index daa9f39..b1d6c7b 100644
--- a/src/AlfClient.h
+++ b/src/AlfClient.h
@@ -68,7 +68,7 @@ class RegisterWriteRpc : DimRpcInfoWrapper
 
   void writeRegister(uint64_t registerAddress, uint32_t registerValue)
   {
-    setString((boost::format("0x%x%s0x%x") % registerAddress % argumentSeparator() % registerValue).str());
+    setString((boost::format("0x%x%s0x%x%s") % registerAddress % pairSeparator() % registerValue).str());
     try {
       getString();
     } catch (const AlfException& e) {
diff --git a/src/AlfServer.cxx b/src/AlfServer.cxx
index b7fdf85..1c4ae8d 100644
--- a/src/AlfServer.cxx
+++ b/src/AlfServer.cxx
@@ -44,7 +44,7 @@ std::string AlfServer::registerRead(const std::string& parameter, std::shared_pt
 
 std::string AlfServer::registerWrite(const std::string& parameter, std::shared_ptr<roc::BarInterface> bar2)
 {
-  std::vector<std::string> params = Util::split(parameter, argumentSeparator());
+  std::vector<std::string> params = Util::split(parameter, pairSeparator());
 
   if (params.size() != 2) {
     BOOST_THROW_EXCEPTION(AlfException() << ErrorInfo::Message("Wrong number of parameters for RPC write call"));