diff --git a/src/lib/dns/rrset_collection.h b/src/lib/dns/rrset_collection.h
index 7a3b4ccc42..62dd9a9a23 100644
--- a/src/lib/dns/rrset_collection.h
+++ b/src/lib/dns/rrset_collection.h
@@ -142,7 +142,7 @@ protected:
 
         virtual IterPtr getNext() {
             CollectionMap::iterator it = iter_;
-            it++;
+            ++it;
             return (RRsetCollectionBase::IterPtr(new DnsIter(it)));
         }
 
diff --git a/src/lib/dns/tests/rrset_collection_unittest.cc b/src/lib/dns/tests/rrset_collection_unittest.cc
index 49b7606b14..e17e9e7a02 100644
--- a/src/lib/dns/tests/rrset_collection_unittest.cc
+++ b/src/lib/dns/tests/rrset_collection_unittest.cc
@@ -201,7 +201,7 @@ protected:
 
         virtual IterPtr getNext() {
             MyCollection::iterator it = iter_;
-            it++;
+            ++it;
             return (RRsetCollectionBase::IterPtr(new MyIter(it)));
         }