diff --git a/bind.spec b/bind.spec
index 989efb9..0ce9484 100644
--- a/bind.spec
+++ b/bind.spec
@@ -598,12 +598,15 @@ export TSAN_OPTIONS="log_exe_name=true log_path=ThreadSanitizer exitcode=0"
 
 %if %{with UNITTEST}
   pushd build
+  ORIGFILES=$(ulimit -n)
+  ulimit -n 4096 # Requires on some machines with many cores
   make unit
   e=$?
   if [ "$e" -ne 0 ]; then
     echo "ERROR: this build of BIND failed 'make unit'. Aborting."
     exit $e;
   fi;
+  ulimit -n $ORIGFILES
   popd
 ## End of UNITTEST
 %endif