diff --git a/Makefile b/Makefile
index 044f5bc..f7f24fc 100644
--- a/Makefile
+++ b/Makefile
@@ -37,5 +37,9 @@
 !else
 .POSIX:
 include mk/SingleUnix.mk
+# Extra hack for OpenBSD make.
+ifndef: all
+0: all
+endif: all
 # \
 !endif