diff --git a/ChangeLog b/ChangeLog
index 009a6b4d21..b2be96173c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Mar 26 12:00:47 MST 1998 Nathan Summers <rock@gimp.org>
+
+	* iscissors.c: This should hopefully fix most of the UMRs
+	(uninitialized memory reads) found with Purify.  No noticable
+	change in iscissors's behavior, unfortunately.
+
 Thu Mar 26 13:03:18 EST 1998 Adrian Likins <adrian@gimp.org>
 
 	* app/app_procs.c app/brush_select.c app/brushes.c 
diff --git a/app/iscissors.c b/app/iscissors.c
index 6e65597d85..b12fbc86d1 100644
--- a/app/iscissors.c
+++ b/app/iscissors.c
@@ -458,6 +458,7 @@ tools_new_iscissors ()
   tool->arrow_keys_func = standard_arrow_keys_func;
   tool->cursor_update_func = rect_select_cursor_update;
   tool->control_func = iscissors_control;
+  tool->auto_snap_to = 0;
   
   last_tool = tool;
   
@@ -1889,7 +1890,13 @@ calculate_edge_map (GImage *gimage,
   destPR.data = conv1 + MAX_CHANNELS * (CONV_WIDTH * offy + offx);
   destPR.rowstride = CONV_WIDTH * MAX_CHANNELS;
   destPR.tiles = NULL;
-
+  destPR.bytes = 1;
+  destPR.x = x1;
+  destPR.y = y1;
+  destPR.w = w;
+  destPR.h = h;
+  destPR.dirty = 1;
+  
   for (pr =pixel_regions_register (2, &srcPR, &destPR); pr != NULL; pr = pixel_regions_process (pr))
     gaussian_deriv (&srcPR, &destPR, HORIZONTAL, std_dev);
 
diff --git a/app/tools/gimpiscissorstool.c b/app/tools/gimpiscissorstool.c
index 6e65597d85..b12fbc86d1 100644
--- a/app/tools/gimpiscissorstool.c
+++ b/app/tools/gimpiscissorstool.c
@@ -458,6 +458,7 @@ tools_new_iscissors ()
   tool->arrow_keys_func = standard_arrow_keys_func;
   tool->cursor_update_func = rect_select_cursor_update;
   tool->control_func = iscissors_control;
+  tool->auto_snap_to = 0;
   
   last_tool = tool;
   
@@ -1889,7 +1890,13 @@ calculate_edge_map (GImage *gimage,
   destPR.data = conv1 + MAX_CHANNELS * (CONV_WIDTH * offy + offx);
   destPR.rowstride = CONV_WIDTH * MAX_CHANNELS;
   destPR.tiles = NULL;
-
+  destPR.bytes = 1;
+  destPR.x = x1;
+  destPR.y = y1;
+  destPR.w = w;
+  destPR.h = h;
+  destPR.dirty = 1;
+  
   for (pr =pixel_regions_register (2, &srcPR, &destPR); pr != NULL; pr = pixel_regions_process (pr))
     gaussian_deriv (&srcPR, &destPR, HORIZONTAL, std_dev);
 
diff --git a/app/tools/iscissors.c b/app/tools/iscissors.c
index 6e65597d85..b12fbc86d1 100644
--- a/app/tools/iscissors.c
+++ b/app/tools/iscissors.c
@@ -458,6 +458,7 @@ tools_new_iscissors ()
   tool->arrow_keys_func = standard_arrow_keys_func;
   tool->cursor_update_func = rect_select_cursor_update;
   tool->control_func = iscissors_control;
+  tool->auto_snap_to = 0;
   
   last_tool = tool;
   
@@ -1889,7 +1890,13 @@ calculate_edge_map (GImage *gimage,
   destPR.data = conv1 + MAX_CHANNELS * (CONV_WIDTH * offy + offx);
   destPR.rowstride = CONV_WIDTH * MAX_CHANNELS;
   destPR.tiles = NULL;
-
+  destPR.bytes = 1;
+  destPR.x = x1;
+  destPR.y = y1;
+  destPR.w = w;
+  destPR.h = h;
+  destPR.dirty = 1;
+  
   for (pr =pixel_regions_register (2, &srcPR, &destPR); pr != NULL; pr = pixel_regions_process (pr))
     gaussian_deriv (&srcPR, &destPR, HORIZONTAL, std_dev);