diff --git a/doc/fixes34.4 b/doc/fixes34.4
index 6531f21bd..2c429a4a4 100644
--- a/doc/fixes34.4
+++ b/doc/fixes34.4
@@ -140,6 +140,7 @@ weaken "farming" strategy
 don't suppress corpse if you kill your own steed
 fix typo in tourist quest leader's greeting
 fix grammar for graveyard sounds when polymorphed
+avoid divide by zero crash if Luck drops below -1 while a prayer is in progress
 
 
 Platform- and/or Interface-Specific Fixes
diff --git a/src/pray.c b/src/pray.c
index 500c82f6b..05d544d79 100644
--- a/src/pray.c
+++ b/src/pray.c
@@ -1,4 +1,4 @@
-/*	SCCS Id: @(#)pray.c	3.5	2005/06/24	*/
+/*	SCCS Id: @(#)pray.c	3.5	2005/08/31	*/
 /* Copyright (c) Benson I. Margulies, Mike Stephenson, Steve Linhart, 1989. */
 /* NetHack may be freely redistributed.  See license for details. */
 
@@ -844,8 +844,22 @@ pleased(g_align)
 	    /* if hero was in trouble, but got better, no special favor */
 	    if (p_trouble == 0) pat_on_head = 1;
 	} else {
-	    int action = rn1(Luck + (on_altar() ? 3 + on_shrine() : 2), 1);
+	    int action, prayer_luck;
 
+	    /* Negative luck is normally impossible here (can_pray() forces
+	       prayer failure in that situation), but it's possible for
+	       Luck to drop during the period of prayer occupation and
+	       become negative by the time we get here.  [Reported case
+	       was lawful character whose stinking cloud caused a delayed
+	       killing of a peaceful human, triggering the "murderer"
+	       penalty while successful prayer was in progress.  It could
+	       also happen due to inconvenient timing on Friday 13th, but
+	       the magnitude there (-1) isn't big enough to cause trouble.]
+	       We don't bother remembering start-of-prayer luck, just make
+	       sure it's at least -1 so that Luck+2 is big enough to avoid
+	       a divide by zero crash when generating a random number.  */
+	    prayer_luck = max(Luck, -1);	/* => (prayer_luck + 2 > 0) */
+	    action = rn1(prayer_luck + (on_altar() ? 3 + on_shrine() : 2), 1);
 	    if (!on_altar()) action = min(action, 3);
 	    if (u.ualign.record < STRIDENT)
 		action = (u.ualign.record > 0 || !rnl(2)) ? 1 : 0;