diff --git a/debian/rules b/debian/rules
index eccb45f49..3cbd405af 100755
--- a/debian/rules
+++ b/debian/rules
@@ -9,6 +9,8 @@ export DEB_LDFLAGS_MAINT_APPEND := -Wl,--as-needed
 ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
     NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
     BOOTSTRAP_PARALLEL = --parallel=$(NUMJOBS)
+else
+    NUMJOBS = 1
 endif
 
 BUILD_DATE = $(shell LC_ALL=C date -u "+%B %d, %Y" -d "@$(SOURCE_DATE_EPOCH)")
@@ -51,8 +53,8 @@ override_dh_auto_configure: $(BUILD_FLAGS_FILE)
 
 override_dh_auto_test:
 	# Pass -j1 to "make test" as a workaround, see https://gitlab.kitware.com/cmake/cmake/issues/17165
-	# The tests are still run in parallel as debhelper pass -jX as ARGS to ctest.
-	dh_auto_test --buildsystem=cmake -- -j1 ARGS="-E CTestTestUpload --timeout 5000"
+	# The tests are still run in parallel as -jX is passed via ARGS to ctest.
+	dh_auto_test --buildsystem=cmake -- -j1 ARGS="-E CTestTestUpload --timeout 5000 -j$(NUMJOBS)"
 
 execute_after_dh_auto_clean:
 	rm -f $(BUILD_FLAGS_FILE)