diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index a68c420ad7..5b6fd81a8c 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,7 @@
-August 10, 2009  (Changes by Graf Zahl)
+August 10, 2009
+- Fixed: The UDMF loader did not initialize the sectors' sectornum property.
+
+August 10, 2009  (Changes by Graf Zahl)
 - Fixed: The true color texture compositing code did not clip the edges
   of multipatch textures used as patches on other multipatch textures.
 
diff --git a/src/p_udmf.cpp b/src/p_udmf.cpp
index c7fc0b80f7..a9e6e5eedd 100644
--- a/src/p_udmf.cpp
+++ b/src/p_udmf.cpp
@@ -1020,6 +1020,7 @@ struct UDMFParser
 		sec->nextsec = -1;	//jff 2/26/98 add fields to support locking out
 		sec->prevsec = -1;	// stair retriggering until build completes
 		sec->heightsec = NULL;	// sector used to get floor and ceiling height
+		sec->sectornum = index;
 		if (floordrop) sec->Flags = SECF_FLOORDROP;
 		// killough 3/7/98: end changes