diff --git a/cpp/src/db/MySQLConnectionPool.h b/cpp/src/db/MySQLConnectionPool.h
index bd047d56f848a1661367d64d1c759b6b0ef24a2d..63ae65829d1de652a54a95d64ef4e31f3d33407c 100644
--- a/cpp/src/db/MySQLConnectionPool.h
+++ b/cpp/src/db/MySQLConnectionPool.h
@@ -94,7 +94,7 @@ protected:
 
 private:
     // Number of connections currently in use
-    unsigned int conns_in_use_;
+    int conns_in_use_;
 
     // Our connection parameters
     std::string db_, user_, password_, server_;