diff --git a/include/mapnik/pool.hpp b/include/mapnik/pool.hpp
index f573a19a9..7459fd719 100644
--- a/include/mapnik/pool.hpp
+++ b/include/mapnik/pool.hpp
@@ -100,7 +100,7 @@ public:
         mutex::scoped_lock lock(mutex_);
 #endif
         typename ContType::iterator itr=unusedPool_.begin();
-        for ( ;itr!=unusedPool_.end(); ++itr)
+        while ( itr!=unusedPool_.end())
         { 
 #ifdef MAPNIK_DEBUG
             std::clog<<"borrow "<<(*itr).get()<<"\n";
@@ -116,7 +116,7 @@ public:
 #ifdef MAPNIK_DEBUG
                 std::clog<<"bad connection (erase)" << (*itr).get()<<"\n";
 #endif 
-                unusedPool_.erase(itr);
+                itr=unusedPool_.erase(itr);
             }
         }
         if (usedPool_.size() < maxSize_)