diff --git a/core/main.mk b/core/main.mk
index 5cb160b..fdb1163 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -737,7 +737,7 @@
 modules:
 	@echo "Available sub-modules:"
 	@echo "$(call module-names-for-tag-list,$(ALL_MODULE_TAGS))" | \
-	      sed -e 's/  */\n/g' | sort -u | $(COLUMN)
+	      tr -s ' ' '\n' | sort -u | $(COLUMN)
 
 .PHONY: showcommands
 showcommands: