diff --git a/doc/man/man1/rcontrib.1 b/doc/man/man1/rcontrib.1
index df494eef9..91155b8de 100644
--- a/doc/man/man1/rcontrib.1
+++ b/doc/man/man1/rcontrib.1
@@ -1,4 +1,4 @@
-.\" RCSid "$Id: rcontrib.1,v 1.17 2020/03/14 16:25:46 greg Exp $"
+.\" RCSid "$Id: rcontrib.1,v 1.18 2020/09/09 21:28:19 greg Exp $"
 .TH RCONTRIB 1 5/25/05 RADIANCE
 .SH NAME
 rcontrib - compute contribution coefficients in a RADIANCE scene
@@ -9,6 +9,8 @@ rcontrib - compute contribution coefficients in a RADIANCE scene
 ][
 .B \-V
 ][
+.B "\-t secs"
+][
 .B "\-c count"
 ][
 .B \-fo
@@ -119,6 +121,11 @@ Note that output flushing via zero-direction rays is disabled with
 .I \-c
 set to zero.
 .PP
+If progress reports are desired, the
+.I \-t
+option specifies a time interval in seconds for reports sent to
+standard error.
+.PP
 The output of
 .I rcontrib
 has many potential uses.
diff --git a/doc/notes/ReleaseNotes b/doc/notes/ReleaseNotes
index 3e0e952e1..bab38db01 100644
--- a/doc/notes/ReleaseNotes
+++ b/doc/notes/ReleaseNotes
@@ -2387,3 +2387,6 @@ Version 5.4
 
 Added rcollate -c option to force operation to continue even if it
 seems unnecessary.  Made tool more robust.
+
+Added -t option to rcontrib (and rfluxmtx) to report progress after the
+given number of seconds.
diff --git a/src/rt/rc3.c b/src/rt/rc3.c
index 4be0f8394..3ff7d3291 100644
--- a/src/rt/rc3.c
+++ b/src/rt/rc3.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rc3.c,v 2.23 2018/05/27 18:35:57 greg Exp $";
+static const char RCSid[] = "$Id: rc3.c,v 2.24 2020/09/09 21:28:19 greg Exp $";
 #endif
 /*
  * Accumulate ray contributions for a set of materials
@@ -444,7 +444,7 @@ parental_loop()
 			}
 			put_zero_record(++lastray);
 		}
-		if (raysleft && !--raysleft)
+		if (!morays())
 			break;				/* preemptive EOI */
 	}
 	while (next_child_nq(1) >= 0)		/* empty results queue */
@@ -529,7 +529,7 @@ feeder_loop()
 				lastdone = lastray = 0;
 			ninq = 0;
 		}
-		if (raysleft && !--raysleft)
+		if (!morays())
 			break;				/* preemptive EOI */
 	}
 	if (ninq) {				/* polish off input */
diff --git a/src/rt/rcmain.c b/src/rt/rcmain.c
index e0fbac5f0..a0607d6a3 100644
--- a/src/rt/rcmain.c
+++ b/src/rt/rcmain.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: rcmain.c,v 2.18 2018/01/18 19:43:43 greg Exp $";
+static const char	RCSid[] = "$Id: rcmain.c,v 2.19 2020/09/09 21:28:19 greg Exp $";
 #endif
 /*
  *  rcmain.c - main for rtcontrib ray contribution tracer
@@ -43,6 +43,8 @@ int	using_stdout = 0;		/* are we using stdout? */
 int	imm_irrad = 0;			/* compute immediate irradiance? */
 int	lim_dist = 0;			/* limit distance? */
 
+int	report_intvl = 0;		/* reporting interval (seconds) */
+
 const char	*modname[MAXMODLIST];	/* ordered modifier name list */
 int		nmods = 0;		/* number of modifiers */
 
@@ -295,6 +297,10 @@ main(int argc, char *argv[])
 			check(2,"s");
 			addmodfile(argv[++i], curout, prms, binval, bincnt);
 			break;
+		case 't':			/* reporting interval */
+			check(2,"i");
+			report_intvl = atoi(argv[++i]);
+			break;
 		default:
 			goto badopt;
 		}
diff --git a/src/rt/rcontrib.c b/src/rt/rcontrib.c
index 9c029a4ca..480912cbc 100644
--- a/src/rt/rcontrib.c
+++ b/src/rt/rcontrib.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rcontrib.c,v 2.36 2020/07/20 15:54:29 greg Exp $";
+static const char RCSid[] = "$Id: rcontrib.c,v 2.37 2020/09/09 21:28:19 greg Exp $";
 #endif
 /*
  * Accumulate ray contributions for a set of materials
@@ -172,8 +172,35 @@ addmodfile(char *fname, char *outf, char *prms, char *binv, int bincnt)
 }
 
 
+/* Check if we have any more rays left (and report progress) */
+int
+morays(void)
+{
+	static RNUMBER	total_rays;
+	static time_t	tstart, last_report;
+	time_t		tnow;
+
+	if (!raysleft)
+		return(1);	/* unknown total, so nothing to do or say */
+
+	if (report_intvl > 0 && (tnow = time(0)) >= last_report+report_intvl) {
+		if (!total_rays) {
+			total_rays = raysleft;
+			tstart = tnow;
+		}
+		sprintf(errmsg, "%.2f%% done after %.3f hours",
+				100.-100.*raysleft/total_rays,
+				(1./3600.)*(tnow - tstart));
+		eputs(errmsg);
+		last_report = tnow;
+	}
+	return(--raysleft);
+}
+
+
+/* Quit program */
 void
-quit(			/* quit program */
+quit(
 	int  code
 )
 {
@@ -364,7 +391,7 @@ rcontrib(void)
 		}
 		done_contrib();		/* accumulate/output */
 		++lastdone;
-		if (raysleft && !--raysleft)
+		if (!morays())
 			break;		/* preemptive EOI */
 	}
 	if (nchild != -1 && (accumulate <= 0) | (account < accumulate)) {
diff --git a/src/rt/rcontrib.h b/src/rt/rcontrib.h
index 195480975..7a6109778 100644
--- a/src/rt/rcontrib.h
+++ b/src/rt/rcontrib.h
@@ -1,4 +1,4 @@
-/* RCSid $Id: rcontrib.h,v 2.15 2016/09/12 20:31:34 greg Exp $ */
+/* RCSid $Id: rcontrib.h,v 2.16 2020/09/09 21:28:19 greg Exp $ */
 
 /*
  * Header file for rcontrib modules
@@ -42,6 +42,8 @@ extern long		waitflush;	/* how long until next flush */
 extern RNUMBER		lastray;	/* last ray number sent */
 extern RNUMBER		lastdone;	/* last ray processed */
 
+extern int		report_intvl;	/* reporting interval (seconds) */
+
 typedef double		DCOLOR[3];	/* double-precision color */
 
 /*
@@ -121,6 +123,8 @@ extern void		end_children(int immed);
 
 extern void		put_zero_record(int ndx);
 
+extern int		morays(void);		/* reached end of input? */
+
 extern void		parental_loop(void);	/* controlling process */
 
 extern void		feeder_loop(void);	/* feeder process */
diff --git a/src/util/rfluxmtx.c b/src/util/rfluxmtx.c
index 3e8142e75..3d4d32527 100644
--- a/src/util/rfluxmtx.c
+++ b/src/util/rfluxmtx.c
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rfluxmtx.c,v 2.52 2020/09/07 04:06:17 greg Exp $";
+static const char RCSid[] = "$Id: rfluxmtx.c,v 2.53 2020/09/09 21:28:19 greg Exp $";
 #endif
 /*
  * Calculate flux transfer matrix or matrices using rcontrib
@@ -1308,6 +1308,7 @@ main(int argc, char *argv[])
 		case 'n':		/* options with 1 argument */
 		case 's':
 		case 'o':
+		case 't':
 			na = 2;
 			break;
 		case 'b':		/* special case */