diff --git a/src/configure.in b/src/configure.in
index fbfa37f..c809427 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -3146,6 +3146,7 @@
 AC_CHECK_TYPE(ino_t, long)
 AC_CHECK_TYPE(dev_t, unsigned)
 AC_C_BIGENDIAN(,,,)
+AC_C_INLINE
 
 AC_MSG_CHECKING(for rlim_t)
 if eval "test \"`echo '$''{'ac_cv_type_rlim_t'+set}'`\" = set"; then
@@ -3564,7 +3565,7 @@
 	setpgid setsid sigaltstack sigstack sigset sigsetjmp sigaction \
 	sigvec strcasecmp strerror strftime stricmp strncasecmp \
 	strnicmp strpbrk strtol tgetent towlower towupper iswupper \
-	usleep utime utimes)
+	usleep utime utimes isnan isinf)
 AC_FUNC_FSEEKO
 
 dnl define _LARGE_FILES, _FILE_OFFSET_BITS and _LARGEFILE_SOURCE when