Index: Makefile
--- Makefile.orig
+++ Makefile
@@ -56,7 +56,7 @@ ARCHFLAGS := $(ARCHFLAGS)
 
 OPTFLAGS  ?= -g -O
 
-CFLAGS    += -Wall -Wno-unused-function -Wno-write-strings -Wno-sign-compare $(ARCHFLAGS)
+CFLAGS    += -Wall -Wno-unused-function -Wno-write-strings -Wno-sign-compare -Wno-unused-variable $(ARCHFLAGS)
 ifneq ($(findstring arm,$(shell uname -m)),)
 	CFLAGS += -DABC_MEMALIGN=4
 endif
@@ -77,6 +77,9 @@ 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
@@ -137,12 +140,17 @@ 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