diff --git a/sources/CONTRIBUTION.md b/sources/CONTRIBUTION.md
index 73f867e..2cfe71f 100644
--- a/sources/CONTRIBUTION.md
+++ b/sources/CONTRIBUTION.md
@@ -2,3 +2,6 @@
 
 It is suggested for the new contributors to use the following tools:
 - `clang-format` for all the C files, source and headers.
+
+The codebase is better compiled and checked with `-Wall`. Ideally, no warning
+should show.
diff --git a/sources/Makefile.am b/sources/Makefile.am
index ec3e42b..d9c9bb2 100644
--- a/sources/Makefile.am
+++ b/sources/Makefile.am
@@ -1,18 +1,16 @@
 ACLOCAL_AMFLAGS = -I m4
-SUBDIRS         = libjalali src man test_kit
+SUBDIRS = libjalali src man test_kit
 
 if WANT_PYJALALI
 install-exec-hook:
-	@echo -e "\n###########################\n"\
-"##  Installing Pyjalali  ##\n"\
-"###########################\n"
+	@printf "Installing PyJalali"
 	test -d pyjalali || mkdir pyjalali
-	@$(CP) $(srcdir)/pyjalali/*.py pyjalali
-	@$(CP) $(srcdir)/setup.py .
+	@cp $(srcdir)/pyjalali/*.py pyjalali
+	@cp $(srcdir)/setup.py .
 	LIBJALALI_DIR=$(DESTDIR)$(libdir) \
 	$(PYTHON) setup.py install --prefix=$(DESTDIR)$(exec_prefix) --record=pyinstalled.txt
 
 uninstall-hook:
-	while read -r fn; do $(RM) -rf "$$fn"; done <pyinstalled.txt
-	-$(RMDIR) $(DESTDIR)$(pythondir)/pyjalali && $(RM) pyinstalled.txt
+	while read -r fn; do rm -rf "$$fn"; done <pyinstalled.txt
+	-rmdir $(DESTDIR)$(pythondir)/pyjalali && rm pyinstalled.txt
 endif
diff --git a/sources/configure.ac b/sources/configure.ac
index 63bc0ab..840bd11 100644
--- a/sources/configure.ac
+++ b/sources/configure.ac
@@ -11,9 +11,6 @@ AC_CONFIG_MACRO_DIR([m4])
 AC_PROG_CC
 AC_PROG_INSTALL
 AC_PROG_MAKE_SET
-AC_PATH_PROG(CP, cp, /bin/cp)
-AC_PATH_PROG(RM, rm, /bin/rm)
-AC_PATH_PROG(RMDIR, rmdir, /bin/rmdir)
 
 # Checks for header files.
 AC_CHECK_HEADERS([time.h limits.h stdlib.h string.h sys/time.h unistd.h])
@@ -66,7 +63,4 @@ if test $installpyjalali = "yes"; then
 fi
 AM_CONDITIONAL([WANT_PYJALALI], [test $installpyjalali = "yes"])
 
-AC_PATH_PROG(RM, rm, $FALSE)
-RM="$RM -f"
-
 AC_OUTPUT
diff --git a/sources/libjalali/Makefile.am b/sources/libjalali/Makefile.am
index 078c68a..8309a25 100644
--- a/sources/libjalali/Makefile.am
+++ b/sources/libjalali/Makefile.am
@@ -15,8 +15,5 @@ libjalali_la_SOURCES = jalali.c jtime.c
 #      example...)
 
 libjalali_la_LDFLAGS = -version-info 0:5:0
-includedir= $(prefix)/include/jalali
+includedir = $(prefix)/include/jalali
 include_HEADERS = jalali.h jtime.h jconfig.h
-INCLUDES        =  -I. -I@includedir@
-LIBS            = @LIBS@ $(THREAD_LIBS)
-AM_CFLAGS          = @CFLAGS@ -D_REENTRANT -W -Wall -O2
diff --git a/sources/src/Makefile.am b/sources/src/Makefile.am
index bac165d..a0f242c 100644
--- a/sources/src/Makefile.am
+++ b/sources/src/Makefile.am
@@ -1,11 +1,7 @@
 bin_PROGRAMS = jcal jdate
 
-INCLUDES = -I${top_srcdir} -I${top_srcdir}/libjalali -I@includedir@
-
-AM_CFLAGS = @CFLAGS@ -fno-inline -D_REENTRANT -Wall\
-	-O2 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
+AM_CFLAGS = @CFLAGS@ -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64
 
 jcal_SOURCES = jcal.c
 jdate_SOURCES = jdate.c
-LDADD           = ../libjalali/libjalali.la -L@libdir@
-LIBS            = @LIBS@ $(THREAD_LIBS)
+LDADD = ../libjalali/libjalali.la -L@libdir@
diff --git a/sources/test_kit/jalali/Makefile.am b/sources/test_kit/jalali/Makefile.am
index 1704cb7..2688aa6 100644
--- a/sources/test_kit/jalali/Makefile.am
+++ b/sources/test_kit/jalali/Makefile.am
@@ -1,9 +1,8 @@
 bin_PROGRAMS = elc get_date get_diff jalali_update jyinfo leap sec_converter
 
-INCLUDES = -I${top_srcdir}/libjalali
+AM_CPPFLAGS = -I${top_srcdir}/libjalali
 
-AM_CFLAGS = @CFLAGS@ -fno-inline -D_REENTRANT -Wall \
-	-O2 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
+AM_CFLAGS = @CFLAGS@ -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64
 
 elc_SOURCES = elc.c
 get_date_SOURCES = get_date.c
@@ -13,4 +12,4 @@ jyinfo_SOURCES = jyinfo.c
 leap_SOURCES = leap.c
 sec_converter_SOURCES = sec_converter.c
 
-LDADD           = ../../libjalali/libjalali.la
+LDADD = ../../libjalali/libjalali.la
diff --git a/sources/test_kit/jtime/Makefile.am b/sources/test_kit/jtime/Makefile.am
index 813b9bc..b6c38a0 100644
--- a/sources/test_kit/jtime/Makefile.am
+++ b/sources/test_kit/jtime/Makefile.am
@@ -1,9 +1,8 @@
 bin_PROGRAMS = jasctime jctime jgmtime jstrftime jstrptime jlocaltime jmktime
 
-INCLUDES = -I${top_srcdir}/libjalali
+AM_CPPFLAGS = -I${top_srcdir}/libjalali
 
-AM_CFLAGS = @CFLAGS@ -fno-inline -D_REENTRANT -Wall \
-	-O2 -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE
+AM_CFLAGS = @CFLAGS@ -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64
 
 jasctime_SOURCES = jasctime.c
 jctime_SOURCES = jctime.c
@@ -13,4 +12,4 @@ jstrptime_SOURCES = jstrptime.c
 jlocaltime_SOURCES = jlocaltime.c
 jmktime_SOURCES = jmktime.c
 
-LDADD           = ../../libjalali/libjalali.la -lreadline
+LDADD = ../../libjalali/libjalali.la -lreadline