diff --git a/src/tools/jam/jam.h b/src/tools/jam/jam.h
index d309b67d6e..c35589e2f7 100644
--- a/src/tools/jam/jam.h
+++ b/src/tools/jam/jam.h
@@ -449,7 +449,7 @@
  */
 
 # ifndef MAXLINE
-# define MAXLINE 10240	/* longest 'together' actions' */
+# define MAXLINE 20480	/* longest 'together' actions' */
 # endif
 
 # ifndef EXITOK