diff --git a/Makefile b/Makefile
index 00a3533..1e20af8 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,5 @@
+.error : This Makefile needs GNU make
+
 CFLAGS+=-g -O2 -Wall -Wno-switch -Wextra -fstack-protector-strong -D_FORTIFY_SOURCE=2
 LDLIBS=-lrt
 ifdef OPENBSD