diff --git a/ghc-rpm-macros.spec b/ghc-rpm-macros.spec
index ee069d3..909ee81 100644
--- a/ghc-rpm-macros.spec
+++ b/ghc-rpm-macros.spec
@@ -7,8 +7,8 @@
 %endif
 
 Name:           ghc-rpm-macros
-Version:        2.4.4
-Release:        2%{?dist}
+Version:        2.4.5
+Release:        1%{?dist}
 Summary:        RPM macros for building Haskell packages for GHC
 
 License:        GPLv3+
@@ -193,6 +193,9 @@ EOF
 
 
 %changelog
+* Thu Sep 15 2022 Jens Petersen <petersen@redhat.com> - 2.4.5-1
+- define ghc_smp_mflags to speed up package builds
+
 * Sat Aug  6 2022 Jens Petersen <petersen@redhat.com> - 2.4.4-2
 - F36 obsoletes regex-applicative-text
 
diff --git a/macros.ghc-os b/macros.ghc-os
index 246a916..eed9e34 100644
--- a/macros.ghc-os
+++ b/macros.ghc-os
@@ -11,3 +11,6 @@
 
 # enable library documentation in doc subpkgs
 %with_haddock 1
+
+# %%{?_smp_ncpus_max:--jobs=%%{?_smp_ncpus_max}}
+%ghc_smp_mflags %{?_smp_mflags}