diff --git a/Makefile b/Makefile
index f47094a..4d8bf72 100644
--- a/Makefile
+++ b/Makefile
@@ -1,14 +1,31 @@
+# For MacPorts iconv PREFIX=/opt/local 
+# Set on command if necessary 
+# make PREFIX=/opt/local
+
 CC = gcc
 CFLAGS = -Wall -D_FILE_OFFSET_BITS=64
+LDLIBS = -lm
+
+ifdef PREFIX 
+  CFLAGS += -I$(PREFIX)/include
+  LDLIBS += -L$(PREFIX)/lib
+endif
+
+UNAME_S := $(shell uname -s)
+ifeq ($(UNAME_S),Darwin)
+  LDLIBS += -liconv
+endif
+
 GIMGLIB_SOURCES = gimglib.c util.c sf_typ.c sf_mps.c sf_tre.c sf_rgn.c sf_lbl.c sf_net.c sf_nod.c sf_dem.c sf_mar.c sf_gmp.c
 GIMGLIB_OBJS = $(GIMGLIB_SOURCES:.c=.o)
 
 all: gimginfo gimgfixcmd gimgxor gimgunlock gimgch gimgextract cmdc
 
 gimginfo: gimginfo.o $(GIMGLIB_OBJS)
+	$(CC) $(CFLAGS) -o $@ $^ $(LDLIBS)
 
 gimgfixcmd: gimgfixcmd.o cmdlib.o $(GIMGLIB_OBJS)
-	$(CC) -o $@ $^ -lm
+	$(CC) $(CFLAGS) -o $@ $^ $(LDLIBS)
 
 gimgxor: gimgxor.o
 
@@ -19,7 +36,7 @@ gimgch: gimgch.o util_indep.o
 gimgextract: gimgextract.o util_indep.o
 
 cmdc: cmdc.o
-	$(CC) -o $@ $< -lm
+	$(CC) $(CFLAGS) -o $@ $< $(LDLIBS)
 
 .PHONY: clean
 clean: