--- a/configure.in
+++ b/configure.in
@@ -21,7 +21,7 @@
 dnl along with Octave; see the file COPYING.  If not, write to the Free
 dnl Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 dnl
-AC_REVISION($Revision: 1.45 $)dnl
+AC_REVISION($Revision: 1.46 $)dnl
 AC_PREREQ(1.8)dnl
 AC_INIT(src/octave.cc)
 AC_CONFIG_HEADER(config.h kpathsea/c-auto.h)
@@ -533,6 +533,11 @@
 AC_HAVE_FUNCS(infinity quiet_nan)dnl
 AC_HAVE_FUNCS(erf erfc lgamma)dnl
 dnl
+AC_COMPILE_CHECK([signgam declaration in math.h],
+  [#include <math.h>],
+  [int foo = signgam + 1;],
+  AC_DEFINE(SIGNGAM_DECLARED, 1), [])dnl
+dnl
 CFLAGS="$XCFLAGS"
 dnl
 dnl Check for nonstandard but common trig functions that we need.