diff --git a/WWWORKER-overwrites-runtime.NumCPU.patch b/WWWORKER-overwrites-runtime.NumCPU.patch
new file mode 100644
index 0000000..e430a1d
--- /dev/null
+++ b/WWWORKER-overwrites-runtime.NumCPU.patch
@@ -0,0 +1,75 @@
+From 53f6f72917211903d2f068b48ed552a6e0e98734 Mon Sep 17 00:00:00 2001
+From: Christian Goll <cgoll@suse.com>
+Date: Wed, 26 Feb 2025 17:07:31 +0100
+Subject: [PATCH] WWWORKER overwrites runtime.NumCPU
+
+runtime.NumCPU varies for different build hosts, so the
+environment variable WWWORKER can be set to keep this number
+constant as this number ends up in
+docs/man/man1/wwctl-overlay-build.1
+and so in the packages
+
+Signed-off-by: Christian Goll <cgoll@suse.com>
+---
+ CHANGELOG.md                             |  1 +
+ Makefile                                 |  2 +-
+ internal/app/wwctl/overlay/build/root.go | 10 +++++++++-
+ 3 files changed, 11 insertions(+), 2 deletions(-)
+
+diff --git a/CHANGELOG.md b/CHANGELOG.md
+index 93b7700a..3ea71b31 100644
+--- a/CHANGELOG.md
++++ b/CHANGELOG.md
+@@ -60,6 +60,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+ - Fix timeout problem for wwclient. #1741
+ - Fixed default "true" state of NetDev.OnBoot. #1754
+ - Port NFS mounts during `wwctl upgrade nodes` before applying defaults. #1758
++- Set WWWORKER from commandline for reproducible builds
+ 
+ ### Removed
+ 
+diff --git a/Makefile b/Makefile
+index 245bdc64..88bc7921 100644
+--- a/Makefile
++++ b/Makefile
+@@ -73,7 +73,7 @@ wwapird: $(config) $(apiconfig) $(call godeps,internal/app/api/wwapird/wwapird.g
+ .PHONY: man_pages
+ man_pages: wwctl $(wildcard docs/man/man5/*.5)
+ 	mkdir -p docs/man/man1
+-	./wwctl --emptyconf genconfig man docs/man/man1
++	WWWORKER=8 ./wwctl --emptyconf genconfig man docs/man/man1
+ 	gzip --force docs/man/man1/*.1
+ 	for manpage in docs/man/man5/*.5; do gzip <$${manpage} >$${manpage}.gz; done
+ 
+diff --git a/internal/app/wwctl/overlay/build/root.go b/internal/app/wwctl/overlay/build/root.go
+index ba1fe163..f41e0132 100644
+--- a/internal/app/wwctl/overlay/build/root.go
++++ b/internal/app/wwctl/overlay/build/root.go
+@@ -1,7 +1,9 @@
+ package build
+ 
+ import (
++	"os"
+ 	"runtime"
++	"strconv"
+ 
+ 	"github.com/spf13/cobra"
+ 	"github.com/warewulf/warewulf/internal/app/wwctl/completions"
+@@ -29,7 +31,13 @@ func init() {
+ 	}
+ 	baseCmd.PersistentFlags().StringVarP(&OverlayDir, "output", "o", "", `Do not create an overlay image for distribution but write to
+ 	the given directory. An overlay must also be ge given to use this option.`)
+-	baseCmd.PersistentFlags().IntVar(&Workers, "workers", runtime.NumCPU(), "The number of parallel workers building overlays")
++	workers := runtime.NumCPU()
++	numCPU := os.Getenv("WWWORKER")
++	wwWorker, err := strconv.Atoi(numCPU)
++	if err == nil {
++		workers = wwWorker
++	}
++	baseCmd.PersistentFlags().IntVar(&Workers, "workers", workers, "The number of parallel workers building overlays")
+ }
+ 
+ // GetRootCommand returns the root cobra.Command for the application.
+-- 
+2.43.0
+
diff --git a/warewulf4.changes b/warewulf4.changes
index 5172df6..fb1c2ef 100644
--- a/warewulf4.changes
+++ b/warewulf4.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Wed Feb 26 16:26:11 UTC 2025 - Christian Goll <cgoll@suse.com>
+
+- added WWWORKER-overwrites-runtime.NumCPU.patch for reproducible
+  builds
+
 -------------------------------------------------------------------
 Tue Feb 25 14:13:23 UTC 2025 - Christian Goll <cgoll@suse.com>
 
diff --git a/warewulf4.spec b/warewulf4.spec
index 937428d..c3de9c2 100644
--- a/warewulf4.spec
+++ b/warewulf4.spec
@@ -42,6 +42,7 @@ Source10:       config-ww4.sh
 Source11:       adjust_overlays.sh
 Source20:       README.dnsmasq
 Source21:       README.RKE2.md
+Patch0:         WWWORKER-overwrites-runtime.NumCPU.patch
 
 BuildRequires:  distribution-release
 BuildRequires:  dracut