--- a/calendarfunc.c
+++ b/calendarfunc.c
@@ -22,7 +22,7 @@
 
 #include "calendarfunc.h"
 #include <stdio.h>
-
+#include <math.h>
 
 
 long persian_jdn(struct icaltimetype dt)
--- a/dockapp.c
+++ b/dockapp.c
@@ -23,6 +23,7 @@
  * modified by Seiichi SATO <ssato@sh.rim.or.jp>
  */
 
+#include <stdlib.h>
 #include "dockapp.h"
 
 #define WINDOWED_SIZE_W 64
--- a/Makefile
+++ b/Makefile
@@ -1,19 +1,15 @@
-CC     = gcc
+CC     ?= gcc
 INCLUDES  = `pkg-config --cflags gtk+-2.0` -I. 
-LFLAGS = `pkg-config --libs gtk+-2.0`
 
 # for BSD
 #INCLUDES = `gtk12-config --cflags` -I. 
 #LFLAGS = `gtk12-config --libs`
-X11BASE = /usr/X11R6
-CFLAGS =  $(INCLUDES) -DICON_TYPE=$(ICON_TYPE)
-INCDIR = -I$(X11BASE)/include/X11 -I$(X11BASE)/include -I$/usr/include -I$/usr/local/include
-DESTDIR= /usr/local
-LIBDIR = -L/usr/lib -L${X11BASE}/lib -L/usr/local/lib
+CFLAGS +=  $(INCLUDES) -DICON_TYPE=$(ICON_TYPE)
+PREFIX = /usr
 PACKAGE = wmCalendar
 
 # for Linux
-LIBS   = $(LIBDIR) -lXpm -lical -lpthread
+LIBS   = -lpthread -lm $(shell $(PKG_CONFIG) --libs gtk+-2.0 x11 xpm xext libical)
 # for Solaris (untested!!!)
 # LIBS   = -lXpm -lX11 -lXext -lsocket -lnsl -lical
 
@@ -30,7 +26,7 @@
 all:	wmCalendar.o wmCalendar 
 
 wmCalendar: $(OBJECTS) 
-	 $(CC) $(COPTS)  $(SYSTEM) $(LFLAGS) -o $@ $(OBJECTS) -o wmCalendar $(INCDIR)$(LIBDIR) $(LIBS)
+	 $(CC) $(CFLAGS) $(LDFLAGS) $(OBJECTS) $(LIBS) -o $@
 
 wmCalendar.o: wmCalendar_master.xpm   wmCalendar_master2.xpm
 clean:
@@ -40,6 +36,8 @@
 	rm -f wmCalendar
 
 install:: wmCalendar
-	install -c -s -m 0755 wmCalendar $(DESTDIR)/bin/
-	install -c -m 0644 wmCalendar.1 $(DESTDIR)/man/man1 
+	install -d $(DESTDIR)$(PREFIX)/bin
+	install -m 0755 wmCalendar $(DESTDIR)$(PREFIX)/bin
+	install -d $(DESTDIR)$(PREFIX)/share/man/man1
+	install -m 0644 wmCalendar.1 $(DESTDIR)$(PREFIX)/share/man/man1