diff --git a/ChangeLog b/ChangeLog
index 38fcde83f..7173a79c7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2010-05-20  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Fix the --enable-optimizations check.
+
+	* m4/gccoptim.m4: Add missing AC_LANG_PUSH/AC_LANG_POP around the
+	C test.  It was using the C++ compiler instead...
+
 2010-04-16  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	* NEWS: Typo.
diff --git a/m4/gccoptim.m4 b/m4/gccoptim.m4
index f2d844db0..07753658b 100644
--- a/m4/gccoptim.m4
+++ b/m4/gccoptim.m4
@@ -11,6 +11,7 @@ AC_DEFUN([ad_GCC_OPTIM],
 int main(int argc, char *argv[]) { return argv[argc-1] == 0; }
 EOF
   changequote([,])dnl
+  AC_LANG_PUSH([C])
   cf_save_CFLAGS="$CFLAGS"
   ac_cv_prog_gcc_opt_flags="-O3"
   for cf_opt in \
@@ -24,6 +25,7 @@ EOF
     fi
   done
   rm -f conftest*
+  AC_LANG_POP([C])
   CFLAGS="$cf_save_CFLAGS $ac_cv_prog_gcc_opt_flags"])
   AC_CACHE_CHECK([for g++ optimization options], ac_cv_prog_gxx_opt_flags,
   [changequote(,)dnl