diff --git a/ChangeLog b/ChangeLog
index 47ae65d8..3a4f2a3f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,11 @@
 	* gpgme.spec.in: Changed user name in Wojciech Polak's email
 	address from ghostface to polak per request by himself.
 
+2002-08-28  Werner Koch  <wk@gnupg.org>
+
+	* acinclude.m4 (GNUPG_CHECK_VA_COPY): New.
+	* configure.ac: Use it.
+
 2002-08-23  Werner Koch  <wk@gnupg.org>
 
 	* configure.ac (GPGME_CONFIG_CFLAGS): Renamed from GPGME_CFLAGS
diff --git a/acinclude.m4 b/acinclude.m4
index b6f0a3a6..6a06343c 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -4143,3 +4143,38 @@ else
 fi
 AC_MSG_RESULT([$SED])
 ])
+
+dnl GNUPG_CHECK_VA_COPY()
+dnl   Do some check on how to implement va_copy.
+dnl   May define MUST_COPY_VA_BY_VAL.
+dnl   Actual test code taken from glib-1.1.
+AC_DEFUN(GNUPG_CHECK_VA_COPY,
+[ AC_MSG_CHECKING(whether va_lists must be copied by value)
+  AC_CACHE_VAL(gnupg_cv_must_copy_va_byval,[
+    gnupg_cv_must_copy_va_byval=no
+    AC_TRY_RUN([
+       #include <stdarg.h>
+       void f (int i, ...)
+       {
+          va_list args1, args2;
+          va_start (args1, i);
+          args2 = args1;
+          if (va_arg (args2, int) != 42 || va_arg (args1, int) != 42)
+            exit (1);
+          va_end (args1);
+          va_end (args2);
+       }
+      
+       int main()
+       {
+          f (0, 42);
+            return 0;
+       }
+    ],gnupg_cv_must_copy_va_byval=yes)
+  ])
+  if test "$gnupg_cv_must_copy_va_byval" = yes; then
+     AC_DEFINE(MUST_COPY_VA_BYVAL,1,[used to implement the va_copy macro])
+  fi
+  AC_MSG_RESULT($gnupg_cv_must_copy_va_byval)
+])
+
diff --git a/configure.ac b/configure.ac
index 14823f82..1ba0f3f9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -154,13 +154,19 @@ dnl
 
 AC_REPLACE_FUNCS(stpcpy)
 
-# asprintf() is at least used in assuan
 AC_REPLACE_FUNCS(vasprintf)
+if test "$ac_cv_func_vasprintf" != yes; then
+  GNUPG_CHECK_VA_COPY
+fi
+
+
+
 # Note: fopencokie is only a dummy stub and not used.  
 #       However some code in assuan/ links against it.
 AC_REPLACE_FUNCS(fopencookie)
 
 
+
 dnl
 dnl Checks for system services
 dnl