diff --git a/build.sh b/build.sh
index 743a2a6845d..7910e278367 100755
--- a/build.sh
+++ b/build.sh
@@ -220,6 +220,8 @@ build_native_corert()
     # processors available to a single process.
     if [ `uname` = "FreeBSD" ]; then
         NumProc=`sysctl hw.ncpu | awk '{ print $2+1 }'`
+    elif [ `uname` = "NetBSD" ]; then
+        NumProc=$(($(getconf NPROCESSORS_ONLN)+1))
     else
         NumProc=$(($(getconf _NPROCESSORS_ONLN)+1))
     fi