diff --git a/doc/fixes37.0 b/doc/fixes37.0
index 7717b9402..8de75e918 100644
--- a/doc/fixes37.0
+++ b/doc/fixes37.0
@@ -1,4 +1,4 @@
-$NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.170 $ $NHDT-Date: 1586375530 2020/04/08 19:52:10 $
+$NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.171 $ $NHDT-Date: 1586382777 2020/04/08 21:52:57 $
 
 General Fixes and Modified Features
 -----------------------------------
@@ -167,6 +167,7 @@ fix door created into random wall or position opening into solid wall
 'use_inverse' option was accidentally made Windows-only; change it back to
 	being more general; change its default to True
 change inconsistent achievement spelling of "Mine Town" to "Minetown"
+fix crash in water_damage_chain
 X11: was still initializing map to 'stone' instead of 'unexplored' after they
 	became separate glyphs
 X11: for text map without color, add support for black&white ice; draw it in
diff --git a/src/trap.c b/src/trap.c
index 948d814d3..d4e9af94d 100644
--- a/src/trap.c
+++ b/src/trap.c
@@ -1,4 +1,4 @@
-/* NetHack 3.6	trap.c	$NHDT-Date: 1586285683 2020/04/07 18:54:43 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.357 $ */
+/* NetHack 3.6	trap.c	$NHDT-Date: 1586382778 2020/04/08 21:52:58 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.358 $ */
 /* Copyright (c) Stichting Mathematisch Centrum, Amsterdam, 1985. */
 /*-Copyright (c) Robert Patrick Rankin, 2013. */
 /* NetHack may be freely redistributed.  See license for details. */
@@ -3682,6 +3682,9 @@ boolean here;
     struct obj *otmp;
     xchar x, y;
 
+    if (!obj)
+        return;
+
     /* initialize acid context: so far, neither seen (dknown) potions of
        acid nor unseen have exploded during this water damage sequence */
     g.acid_ctx.dkn_boom = g.acid_ctx.unk_boom = 0;