diff --git a/src/pl-incl.h b/src/pl-incl.h
index 3b251d1d10..ea7eb993b6 100644
--- a/src/pl-incl.h
+++ b/src/pl-incl.h
@@ -1602,7 +1602,7 @@ struct mark
 
 struct functor
 { word		definition;	/* Tagged definition pointer */
-  word		arguments[1];	/* arguments vector */
+  word		arguments[];	/* arguments vector */
 };
 
 struct clause_bucket