$OpenBSD: patch-Makefile,v 1.1.1.1 2018/08/08 15:24:47 bcallah Exp $

Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -75,6 +75,9 @@ endif
 
 ABC_READLINE_INCLUDES ?=
 ABC_READLINE_LIBRARIES ?= -lreadline
+ifeq ($(OS), OpenBSD)
+  ABC_READLINE_LIBRARIES += -lcurses
+endif
 
 # whether to use libreadline
 ifndef ABC_USE_NO_READLINE
@@ -135,12 +138,17 @@ endif
 
 # LIBS := -ldl -lrt
 LIBS += -lm
-ifneq ($(OS), FreeBSD)
+ifneq ($(OS), $(filter $(OS), FreeBSD OpenBSD))
   LIBS += -ldl
 endif
 
+LIBS += -lrt
+
 ifneq ($(findstring Darwin, $(shell uname)), Darwin)
-   LIBS += -lrt
+   LIBS := $(filter-out -lrt, $(LIBS))
+endif
+ifeq ($(OS), OpenBSD)
+   LIBS := $(filter-out -lrt, $(LIBS))
 endif
 
 ifdef ABC_USE_LIBSTDCXX
