diff --git a/lib/ChangeLog b/lib/ChangeLog
index d1fa0f4..db39f0a 100644
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,5 +1,10 @@
 2004-11-25 Andrew J. Schorr <ajschorr@alumni.princeton.edu>
 
+	* zebra.h: If not C99 and there's no va_copy macro and there is
+	  a __va_copy macro, define va_copy as __va_copy.
+
+2004-11-25 Andrew J. Schorr <ajschorr@alumni.princeton.edu>
+
 	* pid_output.c: (pid_output_lock) Fix 2 bugs: when locking, should
 	  set l_whence to SEEK_SET, not SEEK_END.  And after writing new
 	  pid to file, must ftruncate to eliminate any extraneous bytes left
diff --git a/lib/zebra.h b/lib/zebra.h
index 5d0e238..83da37c 100644
--- a/lib/zebra.h
+++ b/lib/zebra.h
@@ -95,6 +95,12 @@
 
 /* misc include group */
 #include <stdarg.h>
+#if !(defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L)
+/* Not C99; do we need to define va_copy? */
+#if !defined(va_copy) && defined(__va_copy)
+#define va_copy(DST,SRC) __va_copy(DST,SRC)
+#endif /* need va_copy */
+#endif /* !C99 */
 #include "zassert.h"
 
 #ifdef HAVE_LCAPS