diff --git a/debian/changelog b/debian/changelog
index 6c75e5cc..4c68c702 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,9 +1,11 @@
 llvm-toolchain-12 (1:12.0.1-10) UNRELEASED; urgency=medium
 
+  * If parallel is not set in DEB_BUILD_OPTIONS, use nproc
+
   [ John Paul Adrian Glaubitz ]
   * Disable libunwind on sparc, sparc64 and x32
 
- -- John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>  Wed, 29 Sep 2021 18:48:35 +0200
+ -- Sylvestre Ledru <sylvestre@debian.org>  Sat, 02 Oct 2021 10:50:27 +0200
 
 llvm-toolchain-12 (1:12.0.1-9) unstable; urgency=medium
 
diff --git a/debian/rules b/debian/rules
index a8e6dec4..c994960b 100755
--- a/debian/rules
+++ b/debian/rules
@@ -24,6 +24,8 @@ SONAME_OPENMP	:= 5
 DEBIAN_REVISION := $(shell dpkg-parsechangelog |  sed -rne "s,^Version: 1:([0-9.]+)(~|-)(.*),\3,p")
 ifneq (,$(filter parallel=%,$(subst $(COMMA), ,$(DEB_BUILD_OPTIONS))))
   NJOBS := -j $(subst parallel=,,$(filter parallel=%,$(subst $(COMMA), ,$(DEB_BUILD_OPTIONS))))
+else
+  NJOBS := $(shell nproc)
 endif
 
 VENDOR=$(shell lsb_release -is)