diff --git a/include/maxscale/queryclassifier.hh b/include/maxscale/queryclassifier.hh
index df0a4f63b..c07f211b0 100644
--- a/include/maxscale/queryclassifier.hh
+++ b/include/maxscale/queryclassifier.hh
@@ -15,6 +15,7 @@
 #include <maxscale/cppdefs.hh>
 #include <string>
 #include <tr1/memory>
+#include <tr1/unordered_map>
 #include <tr1/unordered_set>
 #include <maxscale/router.h>
 #include <maxscale/session.h>
@@ -156,6 +157,23 @@ public:
     void ps_erase(std::string id);
     void ps_erase(uint32_t id);
 
+    /**
+     * @brief Get the internal ID for the given binary prepared statement
+     *
+     * @param buffer Buffer containing a binary protocol statement other than COM_STMT_PREPARE
+     *
+     * @return The internal ID of the prepared statement that the buffer contents refer to
+     */
+    uint32_t ps_id_internal_get(GWBUF* pBuffer);
+
+    /**
+     * @brief Store a mapping from an external id to the corresponding internal id
+     *
+     * @param external_id  The external id as seen by the client.
+     * @param internal_id  The corresponding internal id.
+     */
+    void ps_id_internal_put(uint32_t external_id, uint32_t internal_id);
+
     uint32_t get_route_target(uint8_t command, uint32_t qtype);
 
     MXS_SESSION* session() const
@@ -167,6 +185,8 @@ private:
     class PSManager;
     typedef std::shared_ptr<PSManager> SPSManager;
 
+    typedef std::tr1::unordered_map<uint32_t, uint32_t> HandleMap;
+
 private:
     MXS_SESSION*      m_pSession;
     mxs_target_t      m_use_sql_variables_in;
@@ -177,6 +197,7 @@ private:
     bool              m_large_query;              /**< Set to true when processing payloads >= 2^24 bytes */
     bool              m_multi_statements_allowed; /**< Are multi-statements allowed */
     SPSManager        m_sPs_manager;
+    HandleMap         m_ps_handles;               /** External ID to internal ID */
 };
 
 }
diff --git a/server/core/queryclassifier.cc b/server/core/queryclassifier.cc
index 49cbe116d..b62512596 100644
--- a/server/core/queryclassifier.cc
+++ b/server/core/queryclassifier.cc
@@ -364,5 +364,52 @@ uint32_t QueryClassifier::get_route_target(uint8_t command, uint32_t qtype)
     return target;
 }
 
+namespace
+{
+
+// Copy of mxs_mysql_extract_ps_id() in modules/protocol/MySQL/mysql_common.cc,
+// but we do not want to create a dependency from maxscale-common to that.
+
+uint32_t mysql_extract_ps_id(GWBUF* buffer)
+{
+    uint32_t rval = 0;
+    uint8_t id[MYSQL_PS_ID_SIZE];
+
+    if (gwbuf_copy_data(buffer, MYSQL_PS_ID_OFFSET, sizeof(id), id) == sizeof(id))
+    {
+        rval = gw_mysql_get_byte4(id);
+    }
+
+    return rval;
+}
+
+}
+
+uint32_t QueryClassifier::ps_id_internal_get(GWBUF* pBuffer)
+{
+    uint32_t internal_id = 0;
+
+    // All COM_STMT type statements store the ID in the same place
+    uint32_t external_id = mysql_extract_ps_id(pBuffer);
+    auto it = m_ps_handles.find(external_id);
+
+    if (it != m_ps_handles.end())
+    {
+        internal_id = it->second;
+    }
+    else
+    {
+        MXS_WARNING("Client requests unknown prepared statement ID '%u' that "
+                    "does not map to an internal ID", external_id);
+    }
+
+    return internal_id;
+}
+
+void QueryClassifier::ps_id_internal_put(uint32_t external_id, uint32_t internal_id)
+{
+    m_ps_handles[external_id] = internal_id;
+}
+
 }
 
diff --git a/server/modules/routing/readwritesplit/routeinfo.cc b/server/modules/routing/readwritesplit/routeinfo.cc
index b0c0e5fbf..b9d7181a2 100644
--- a/server/modules/routing/readwritesplit/routeinfo.cc
+++ b/server/modules/routing/readwritesplit/routeinfo.cc
@@ -613,7 +613,7 @@ route_target_t get_target_type(RWSplitSession *rses, GWBUF *buffer,
             }
             else if (mxs_mysql_is_ps_command(*command))
             {
-                *stmt_id = get_internal_ps_id(rses, buffer);
+                *stmt_id = rses->qc().ps_id_internal_get(buffer);
                 *type = rses->qc().ps_get_type(*stmt_id);
             }
 
diff --git a/server/modules/routing/readwritesplit/rwsplit_session_cmd.cc b/server/modules/routing/readwritesplit/rwsplit_session_cmd.cc
index 9b6b574ed..88531c180 100644
--- a/server/modules/routing/readwritesplit/rwsplit_session_cmd.cc
+++ b/server/modules/routing/readwritesplit/rwsplit_session_cmd.cc
@@ -111,7 +111,7 @@ void RWSplitSession::process_sescmd_response(SRWBackend& backend, GWBUF** ppPack
                     {
                         /** Map the returned response to the internal ID */
                         MXS_INFO("PS ID %u maps to internal ID %lu", resp.id, id);
-                        m_ps_handles[resp.id] = id;
+                        m_qc.ps_id_internal_put(resp.id, id);
                     }
 
                     // Discard any slave connections that did not return the same result
diff --git a/server/modules/routing/readwritesplit/rwsplitsession.cc b/server/modules/routing/readwritesplit/rwsplitsession.cc
index 1655ceeee..2d15f4a85 100644
--- a/server/modules/routing/readwritesplit/rwsplitsession.cc
+++ b/server/modules/routing/readwritesplit/rwsplitsession.cc
@@ -737,24 +737,3 @@ void RWSplitSession::handle_error_reply_client(DCB *backend_dcb, GWBUF *errmsg)
         m_client->func.write(m_client, gwbuf_clone(errmsg));
     }
 }
-
-uint32_t get_internal_ps_id(RWSplitSession* rses, GWBUF* buffer)
-{
-    uint32_t rval = 0;
-
-    // All COM_STMT type statements store the ID in the same place
-    uint32_t id = mxs_mysql_extract_ps_id(buffer);
-    ClientHandleMap::iterator it = rses->m_ps_handles.find(id);
-
-    if (it != rses->m_ps_handles.end())
-    {
-        rval = it->second;
-    }
-    else
-    {
-        MXS_WARNING("Client requests unknown prepared statement ID '%u' that "
-                    "does not map to an internal ID", id);
-    }
-
-    return rval;
-}