diff --git a/ChangeLog b/ChangeLog
index 9d01b8e6..e479adf5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -11,7 +11,7 @@
 - better cache sizing for vips_resize()
 - sizealike / formatalike / bandsalike elide completely if they can for
   a x2 saving in C stack use in many cases
-- added vips_mapim() ... resample with an index image
+- added vips_mapim() ... resample with an index image, plus test
 
 7/5/15 started 8.1.1
 - oop, vips-8.0 wrapper script should be vips-8.1, thanks Danilo
diff --git a/TODO b/TODO
index 87653b67..61488738 100644
--- a/TODO
+++ b/TODO
@@ -1,7 +1,9 @@
-- black lines in to_polar ... investigate
-
 - easy to get a segv with Nicolas's interpolators, argh
 
+  just with float images?
+
+  try to_polar, set LBB, zoom in and scroll around a bit
+
 - speed up rect with atan2?
 
 - vips_resize() should not use the anti-alias filter if vips_shrink() has
diff --git a/libvips/resample/mapim.c b/libvips/resample/mapim.c
index 8c6636ff..f40d2ccc 100644
--- a/libvips/resample/mapim.c
+++ b/libvips/resample/mapim.c
@@ -182,9 +182,9 @@ vips_mapim_region_minmax( VipsRegion *region, VipsRect *r, VipsRect *bounds )
 		TYPE py = p1[1]; \
 		\
 		if( px < 0 || \
-			px > resample->in->Xsize - 1 || \
+			px > resample->in->Xsize || \
 			py < 0 || \
-			py > resample->in->Ysize - 1 ) { \
+			py > resample->in->Ysize ) { \
 			for( z = 0; z < ps; z++ )  \
 				q[z] = 0; \
 		} \
@@ -295,6 +295,7 @@ vips_mapim_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
 		case VIPS_FORMAT_FLOAT: 		
 		case VIPS_FORMAT_COMPLEX: 
 			LOOKUP( float ); break; 
+			break;
 
 		case VIPS_FORMAT_DOUBLE:	
 		case VIPS_FORMAT_DPCOMPLEX: