diff --git a/debian/changelog b/debian/changelog
index 830a44a8..769f34ff 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -6,6 +6,7 @@ llvm-toolchain-9 (1:9.0.1~+rc2-1~exp2) UNRELEASED; urgency=medium
     path-hurd.diff, libcxxabi-arm-ehabi-fix.patch, libcxxabi-test-don-t-
     fail-extended-long-double.patch, revert-change-soname.diff, try-to-
     unbreak-thinlto.diff that are missing from debian/patches/series.
+  * Rely on pre-initialized dpkg-architecture variables.
 
  -- Sylvestre Ledru <sylvestre@debian.org>  Sun, 08 Dec 2019 21:02:49 +0100
 
diff --git a/debian/rules b/debian/rules
index 720fa540..438f276a 100755
--- a/debian/rules
+++ b/debian/rules
@@ -33,11 +33,7 @@ DISTRO=$(shell lsb_release -sc)
 
 DH_VERSION := $(shell dpkg -s debhelper | grep '^Version' | awk '{print $$2}')
 
-DEB_HOST_MULTIARCH  ?= $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
-DEB_HOST_GNU_TYPE   ?= $(shell dpkg-architecture -qDEB_HOST_GNU_TYPE)
-DEB_HOST_ARCH_BITS  ?= $(shell dpkg-architecture -qDEB_HOST_ARCH_BITS)
-DEB_HOST_ARCH       ?= $(shell dpkg-architecture -qDEB_HOST_ARCH)
-DEB_HOST_ARCH_OS    ?= $(shell dpkg-architecture -qDEB_HOST_ARCH_OS)
+include /usr/share/dpkg/architecture.mk
 
 LDFLAGS_EXTRA =
 CXXFLAGS_EXTRA =