diff --git a/include/notcurses.h b/include/notcurses.h
index 479e69208..454aa6b37 100644
--- a/include/notcurses.h
+++ b/include/notcurses.h
@@ -628,6 +628,16 @@ notcurses_bg_prep(uint64_t* channels, int r, int g, int b){
   return notcurses_channel_prep(channels, CELL_BG_MASK, 0, r, g, b, CELL_BGDEFAULT_MASK);
 }
 
+static inline void
+notcurses_fg_default_prep(uint64_t* channels){
+  *channels &= ~(CELL_FGDEFAULT_MASK);
+}
+
+static inline void
+notcurses_bg_default_prep(uint64_t* channels){
+  *channels &= ~(CELL_BGDEFAULT_MASK);
+}
+
 static inline void
 cell_set_fg(cell* c, unsigned r, unsigned g, unsigned b){
   notcurses_fg_prep(&c->channels, r, g, b);
@@ -661,7 +671,7 @@ cell_inherits_style(const cell* c){
 // use the default color for the foreground
 static inline void
 cell_fg_default(cell* c){
-  c->channels &= ~CELL_FGDEFAULT_MASK;
+  notcurses_fg_default_prep(&c->channels);
 }
 
 // is the cell using the terminal's default foreground color for its foreground?
@@ -673,7 +683,7 @@ cell_fg_default_p(const cell* c){
 // use the default color for the background
 static inline void
 cell_bg_default(cell* c){
-  c->channels &= ~CELL_BGDEFAULT_MASK;
+  notcurses_bg_default_prep(&c->channels);
 }
 
 // is the cell using the terminal's default background color for its background?
diff --git a/src/demo/unicodeblocks.c b/src/demo/unicodeblocks.c
index f559d4286..f9eee32a7 100644
--- a/src/demo/unicodeblocks.c
+++ b/src/demo/unicodeblocks.c
@@ -109,9 +109,17 @@ int unicodeblocks_demo(struct notcurses* nc){
       return -1;
     }
     ++xstart;
+    cell ul = CELL_TRIVIAL_INITIALIZER, ur = CELL_TRIVIAL_INITIALIZER;
+    cell ll = CELL_TRIVIAL_INITIALIZER, lr = CELL_TRIVIAL_INITIALIZER;
+    cell hl = CELL_TRIVIAL_INITIALIZER, vl = CELL_TRIVIAL_INITIALIZER;
+    cells_rounded_box(n, 0, 0, &ul, &ur, &ll, &lr, &hl, &vl);
+    cell_set_bg(&hl, 0, 0, 0);
+    cell_set_bg(&vl, 0, 0, 0);
     if(ncplane_rounded_box_sized(n, 0, 0, BLOCKSIZE / CHUNKSIZE + 2, (CHUNKSIZE * 2) + 2, 0)){
       return -1;
     }
+    cell_release(n, &ul); cell_release(n, &ur); cell_release(n, &hl);
+    cell_release(n, &ll); cell_release(n, &lr); cell_release(n, &vl);
     for(chunk = 0 ; chunk < BLOCKSIZE / CHUNKSIZE ; ++chunk){
       if(ncplane_cursor_move_yx(n, 4 + chunk, xstart)){
         return -1;