diff --git a/src/ca/netReadCopyIO.cpp b/src/ca/netReadCopyIO.cpp
index 67e9c6c3b..a418b1bcd 100644
--- a/src/ca/netReadCopyIO.cpp
+++ b/src/ca/netReadCopyIO.cpp
@@ -73,7 +73,7 @@ void netReadCopyIO::exceptionNotify ( int status,
 void netReadCopyIO::show ( unsigned level ) const
 {
     int tmpType = static_cast <int> ( this->type );
-    printf ( "read copy IO at %p, type %s, element count %u\n", 
+    printf ( "read copy IO at %p, type %s, element count %lu\n", 
         this, dbf_type_to_text ( tmpType ), this->count );
     if ( level > 0u ) {
         printf ( "\tsequence number %u, user's storage %p\n",