diff --git a/libvips/resample/bicubic.cpp b/libvips/resample/bicubic.cpp
index 83c71028..22c4f6fb 100644
--- a/libvips/resample/bicubic.cpp
+++ b/libvips/resample/bicubic.cpp
@@ -434,7 +434,11 @@ vips_interpolate_bicubic_class_init( VipsInterpolateBicubicClass *iclass )
 
 	interpolate_class->interpolate   = vips_interpolate_bicubic_interpolate;
 	interpolate_class->window_size   = 4;
-	interpolate_class->window_offset = 1;
+	interpolate_class->window_offset = 2;
+        /*
+         * Note from nicolas: If things were programmed sanely, I
+         * think window_offset should be 1, not 2.
+         */
 
 	/* Build the tables of pre-computed coefficients.
 	 */
diff --git a/libvips/resample/lbb.cpp b/libvips/resample/lbb.cpp
index 1c2ba488..0ca0dcb5 100644
--- a/libvips/resample/lbb.cpp
+++ b/libvips/resample/lbb.cpp
@@ -796,7 +796,11 @@ vips_interpolate_lbb_class_init( VipsInterpolateLbbClass *klass )
 
   interpolate_class->interpolate   = vips_interpolate_lbb_interpolate;
   interpolate_class->window_size   = 4;
-  interpolate_class->window_offset = 1;
+  interpolate_class->window_offset = 2;
+  /*
+   * Note from nicolas: If things were sane, window_offset should be
+   * 1, not 2.
+   */
 }
 
 static void