diff --git a/make/topdir.mk b/make/topdir.mk
index 4f0f2abd..834dc347 100644
--- a/make/topdir.mk
+++ b/make/topdir.mk
@@ -156,7 +156,7 @@ prefix.done:
 	touch $@
 
 echo-prereq-build:
-	@python2 $(MOD_SCRIPT_DIR)/projects.py --topdir . $(PROJECTS_PY_EXTRA_ARGS) requires-pkg $(RPM_PROJECT)
+	@echo $(call proj_query, requires-pkg --flavours "build" $(PROJECT))
 
 list-files echo-files:
 	@$(LIST_VCS_FILES) -f
diff --git a/scripts/pkg-manager.sh b/scripts/pkg-manager.sh
index 9f138124..92a25d6e 100644
--- a/scripts/pkg-manager.sh
+++ b/scripts/pkg-manager.sh
@@ -65,7 +65,7 @@ cmd_install()
 			global_opts="$global_opts --noconfirm"
 			env="$env DEBIAN_FRONTEND=noninteractive"
 		}
-		eval run sudo $env -S pacman $global_opts -S "$@"
+		eval run sudo $env -S pacman $global_opts -S --needed "$@"
 		;;
 	*)
 		fatal "Tried to install on unsupported platform \"$ID\""