--- a/configure.ac
+++ b/configure.ac
@@ -229,7 +229,7 @@ dnl ======================================================================
 dnl functions testing
 dnl ======================================================================
 AX_CREATE_STDINT_H([liblangtag/lt-stdint.h])
-AC_CHECK_HEADERS([dirent.h execinfo.h libgen.h sys/param.h memory.h])
+AC_CHECK_HEADERS([dirent.h dlfcn.h execinfo.h libgen.h sys/param.h memory.h])
 AC_CHECK_FUNCS([backtrace getegid geteuid getgid getuid __secure_getenv secure_getenv strndup vasprintf vsnprintf])
 AC_CHECK_VA_COPY
 
@@ -337,13 +337,13 @@ MODULE_LIBS=
 if test "x$enable_modules" != "xno"; then
 	AC_MSG_CHECKING(for the suffix of module shared libraries)
 	export SED
-	shrext_cmds=`libtool --config | grep '^shrext_cmds='`
+	shrext_cmds=`${SLIBTOOL:-libtool} --config | grep '^shrext_cmds='`
 	eval $shrext_cmds
 	module=yes eval std_shrext=$shrext_cmds
 	lt_module_suffix=`echo $std_shrext | sed 's/^\.//'`
 	AC_MSG_RESULT(.$lt_module_suffix)
 	if test "x$lt_module_suffix" = x; then
-		AC_MSG_ERROR(Unable to determine shared libreary suffix from libtool)
+		AC_MSG_ERROR(Unable to determine shared library suffix from libtool)
 	fi
 	use_modules=0