:: commit f061965f691ff0bd4aef6539ce4588dad72a9b39
build: Add guards to ensure GNU Make is used
diff --git a/Makefile b/Makefile
index 12f74a22..7303aef0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,7 @@
+ifneq (,)
+This makefile requires GNU Make.
+endif
+
PREFIX ?= /usr/local
DESTDIR ?=
diff --git a/decompressor/Makefile b/decompressor/Makefile
index 2ae358a6..bebfe471 100644
--- a/decompressor/Makefile
+++ b/decompressor/Makefile
@@ -1,3 +1,7 @@
+ifneq (,)
+This makefile requires GNU Make.
+endif
+
BUILDDIR =
ifeq ($(BUILDDIR), )
diff --git a/stage23/Makefile b/stage23/Makefile
index e2b4fb15..e266db20 100644
--- a/stage23/Makefile
+++ b/stage23/Makefile
@@ -1,3 +1,7 @@
+ifneq (,)
+This makefile requires GNU Make.
+endif
+
TARGET =
BUILDDIR =
