diff --git a/configure b/configure
index f6823dce786..d3b61a8a417 100755
--- a/configure
+++ b/configure
@@ -11819,7 +11819,6 @@ fi
 
 
 
-# do this one the hard way in case isinf() is a macro
 echo "$as_me:$LINENO: checking for isinf" >&5
 echo $ECHO_N "checking for isinf... $ECHO_C" >&6
 if test "${ac_cv_func_isinf+set}" = set; then
@@ -11828,7 +11827,9 @@ else
   cat >conftest.$ac_ext <<_ACEOF
 #line $LINENO "configure"
 #include "confdefs.h"
+
 #include <math.h>
+double glob_double;
 
 #ifdef F77_DUMMY_MAIN
 #  ifdef __cplusplus
@@ -11839,7 +11840,7 @@ else
 int
 main ()
 {
-double x = 0.0; int res = isinf(x);
+return isinf(glob_double) ? 0 : 1;
   ;
   return 0;
 }
@@ -12454,7 +12455,10 @@ echo $ECHO_N "checking for finite... $ECHO_C" >&6
 cat >conftest.$ac_ext <<_ACEOF
 #line $LINENO "configure"
 #include "confdefs.h"
+
 #include <math.h>
+double glob_double;
+
 #ifdef F77_DUMMY_MAIN
 #  ifdef __cplusplus
      extern "C"
@@ -12464,7 +12468,7 @@ cat >conftest.$ac_ext <<_ACEOF
 int
 main ()
 {
-int dummy=finite(1.0);
+return finite(glob_double) ? 0 : 1;
   ;
   return 0;
 }
diff --git a/configure.in b/configure.in
index 94b0a5085d6..8462fffc434 100644
--- a/configure.in
+++ b/configure.in
@@ -1,5 +1,5 @@
 dnl Process this file with autoconf to produce a configure script.
-dnl $Header: /cvsroot/pgsql/configure.in,v 1.301.2.18 2006/01/05 03:59:47 momjian Exp $
+dnl $Header: /cvsroot/pgsql/configure.in,v 1.301.2.19 2006/01/12 19:24:26 tgl Exp $
 dnl
 dnl Developers, please strive to achieve this order:
 dnl
@@ -912,12 +912,13 @@ AC_CHECK_FUNCS(vsnprintf, [], pgac_need_repl_snprintf=yes)
 AC_CHECK_DECLS([snprintf, vsnprintf])
 
 
-# do this one the hard way in case isinf() is a macro
+dnl Cannot use AC_CHECK_FUNC because isinf may be a macro
 AC_CACHE_CHECK([for isinf], ac_cv_func_isinf,
-[AC_TRY_LINK(
-[#include <math.h>
+[AC_TRY_LINK([
+#include <math.h>
+double glob_double;
 ],
-[double x = 0.0; int res = isinf(x);],
+[return isinf(glob_double) ? 0 : 1;],
 [ac_cv_func_isinf=yes],
 [ac_cv_func_isinf=no])])
 
@@ -974,8 +975,11 @@ fi
 
 dnl Cannot use AC_CHECK_FUNC because finite may be a macro
 AC_MSG_CHECKING(for finite)
-AC_TRY_LINK([#include <math.h>],
-            [int dummy=finite(1.0);],
+AC_TRY_LINK([
+#include <math.h>
+double glob_double;
+],
+            [return finite(glob_double) ? 0 : 1;],
             [AC_DEFINE(HAVE_FINITE, 1, [Define to 1 if you have finite().])
 AC_MSG_RESULT(yes)],
             [AC_MSG_RESULT(no)])