diff --git a/ChangeLog b/ChangeLog
index 557b8b67..4d1588d3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2001-07-18  Akim Demaille  <akim@epita.fr>
+
+	The C-Fortran 77 hooks are available only once AC_F77_DUMMY_MAIN
+	was run, while they are needed also when it is expanded.
+	Reported by Nicolas Joly.
+
+	* aclang.m4 (AC_F77_DUMMY_MAIN): Define _AC_LANG_PROGRAM_C_F77_HOOKS.
+	(AC_LANG_PROGRAM(C)): Use it instead of depending upon
+	AC_F77_DUMMY_MAIN being expanded.
+
 2001-07-18  Akim Demaille  <akim@epita.fr>
 
 	* configure.in: Bump to 2.51a.
diff --git a/aclang.m4 b/aclang.m4
index 4a5b9e26..b360c392 100644
--- a/aclang.m4
+++ b/aclang.m4
@@ -358,14 +358,7 @@ $1])
 # against Fortran code, hence a dummy main might be needed.
 m4_define([AC_LANG_PROGRAM(C)],
 [$1
-m4_provide_ifelse([AC_F77_DUMMY_MAIN],
-[#ifdef F77_DUMMY_MAIN
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int F77_DUMMY_MAIN() { return 1; }
-#endif
-])dnl
+m4_ifdef([_AC_LANG_PROGRAM_C_F77_HOOKS], [_AC_LANG_PROGRAM_C_F77_HOOKS()])dnl
 int
 main ()
 {
@@ -1961,6 +1954,14 @@ AC_LANG_POP(Fortran 77)dnl
 #   MAIN _MAIN __MAIN main_ main__ _main (we follow DDD and try these too)
 AC_DEFUN([AC_F77_DUMMY_MAIN],
 [AC_REQUIRE([AC_F77_LIBRARY_LDFLAGS])dnl
+m4_define([_AC_LANG_PROGRAM_C_F77_HOOKS],
+[#ifdef F77_DUMMY_MAIN
+#  ifdef __cplusplus
+     extern "C"
+#  endif
+   int F77_DUMMY_MAIN() { return 1; }
+#endif
+])
 AC_CACHE_CHECK([for dummy main to link with Fortran 77 libraries],
                ac_cv_f77_dummy_main,
 [AC_LANG_PUSH(C)dnl
diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4
index 4a5b9e26..b360c392 100644
--- a/lib/autoconf/c.m4
+++ b/lib/autoconf/c.m4
@@ -358,14 +358,7 @@ $1])
 # against Fortran code, hence a dummy main might be needed.
 m4_define([AC_LANG_PROGRAM(C)],
 [$1
-m4_provide_ifelse([AC_F77_DUMMY_MAIN],
-[#ifdef F77_DUMMY_MAIN
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int F77_DUMMY_MAIN() { return 1; }
-#endif
-])dnl
+m4_ifdef([_AC_LANG_PROGRAM_C_F77_HOOKS], [_AC_LANG_PROGRAM_C_F77_HOOKS()])dnl
 int
 main ()
 {
@@ -1961,6 +1954,14 @@ AC_LANG_POP(Fortran 77)dnl
 #   MAIN _MAIN __MAIN main_ main__ _main (we follow DDD and try these too)
 AC_DEFUN([AC_F77_DUMMY_MAIN],
 [AC_REQUIRE([AC_F77_LIBRARY_LDFLAGS])dnl
+m4_define([_AC_LANG_PROGRAM_C_F77_HOOKS],
+[#ifdef F77_DUMMY_MAIN
+#  ifdef __cplusplus
+     extern "C"
+#  endif
+   int F77_DUMMY_MAIN() { return 1; }
+#endif
+])
 AC_CACHE_CHECK([for dummy main to link with Fortran 77 libraries],
                ac_cv_f77_dummy_main,
 [AC_LANG_PUSH(C)dnl
diff --git a/lib/autoconf/fortran.m4 b/lib/autoconf/fortran.m4
index 4a5b9e26..b360c392 100644
--- a/lib/autoconf/fortran.m4
+++ b/lib/autoconf/fortran.m4
@@ -358,14 +358,7 @@ $1])
 # against Fortran code, hence a dummy main might be needed.
 m4_define([AC_LANG_PROGRAM(C)],
 [$1
-m4_provide_ifelse([AC_F77_DUMMY_MAIN],
-[#ifdef F77_DUMMY_MAIN
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int F77_DUMMY_MAIN() { return 1; }
-#endif
-])dnl
+m4_ifdef([_AC_LANG_PROGRAM_C_F77_HOOKS], [_AC_LANG_PROGRAM_C_F77_HOOKS()])dnl
 int
 main ()
 {
@@ -1961,6 +1954,14 @@ AC_LANG_POP(Fortran 77)dnl
 #   MAIN _MAIN __MAIN main_ main__ _main (we follow DDD and try these too)
 AC_DEFUN([AC_F77_DUMMY_MAIN],
 [AC_REQUIRE([AC_F77_LIBRARY_LDFLAGS])dnl
+m4_define([_AC_LANG_PROGRAM_C_F77_HOOKS],
+[#ifdef F77_DUMMY_MAIN
+#  ifdef __cplusplus
+     extern "C"
+#  endif
+   int F77_DUMMY_MAIN() { return 1; }
+#endif
+])
 AC_CACHE_CHECK([for dummy main to link with Fortran 77 libraries],
                ac_cv_f77_dummy_main,
 [AC_LANG_PUSH(C)dnl
diff --git a/lib/autoconf/lang.m4 b/lib/autoconf/lang.m4
index 4a5b9e26..b360c392 100644
--- a/lib/autoconf/lang.m4
+++ b/lib/autoconf/lang.m4
@@ -358,14 +358,7 @@ $1])
 # against Fortran code, hence a dummy main might be needed.
 m4_define([AC_LANG_PROGRAM(C)],
 [$1
-m4_provide_ifelse([AC_F77_DUMMY_MAIN],
-[#ifdef F77_DUMMY_MAIN
-#  ifdef __cplusplus
-     extern "C"
-#  endif
-   int F77_DUMMY_MAIN() { return 1; }
-#endif
-])dnl
+m4_ifdef([_AC_LANG_PROGRAM_C_F77_HOOKS], [_AC_LANG_PROGRAM_C_F77_HOOKS()])dnl
 int
 main ()
 {
@@ -1961,6 +1954,14 @@ AC_LANG_POP(Fortran 77)dnl
 #   MAIN _MAIN __MAIN main_ main__ _main (we follow DDD and try these too)
 AC_DEFUN([AC_F77_DUMMY_MAIN],
 [AC_REQUIRE([AC_F77_LIBRARY_LDFLAGS])dnl
+m4_define([_AC_LANG_PROGRAM_C_F77_HOOKS],
+[#ifdef F77_DUMMY_MAIN
+#  ifdef __cplusplus
+     extern "C"
+#  endif
+   int F77_DUMMY_MAIN() { return 1; }
+#endif
+])
 AC_CACHE_CHECK([for dummy main to link with Fortran 77 libraries],
                ac_cv_f77_dummy_main,
 [AC_LANG_PUSH(C)dnl
diff --git a/lib/m4sugar/m4sugar.m4 b/lib/m4sugar/m4sugar.m4
index c06775d8..e25d7da3 100644
--- a/lib/m4sugar/m4sugar.m4
+++ b/lib/m4sugar/m4sugar.m4
@@ -371,7 +371,7 @@ m4_define([m4_ifset],
           [$3])])
 
 
-# ifndef(NAME, [IF-NOT-DEFINED], [IF-DEFINED])
+# m4_ifndef(NAME, [IF-NOT-DEFINED], [IF-DEFINED])
 # -----------------------------------------------
 m4_define([m4_ifndef],
 [m4_ifdef([$1], [$3], [$2])])
diff --git a/m4sugar.m4 b/m4sugar.m4
index c06775d8..e25d7da3 100644
--- a/m4sugar.m4
+++ b/m4sugar.m4
@@ -371,7 +371,7 @@ m4_define([m4_ifset],
           [$3])])
 
 
-# ifndef(NAME, [IF-NOT-DEFINED], [IF-DEFINED])
+# m4_ifndef(NAME, [IF-NOT-DEFINED], [IF-DEFINED])
 # -----------------------------------------------
 m4_define([m4_ifndef],
 [m4_ifdef([$1], [$3], [$2])])