diff --git a/src/demo/yield.c b/src/demo/yield.c
index 518cdbd19..b07ce789d 100644
--- a/src/demo/yield.c
+++ b/src/demo/yield.c
@@ -1,5 +1,67 @@
 #include "demo.h"
 
+#define MAXITER 1024
+
+struct marsh {
+  int total;
+  int maxy;
+  int maxx;
+  struct ncvisual* wmv;   // single, shared between threads
+  struct ncplane* label;  // single, shared between threads
+  struct notcurses* nc;
+  struct ncvisual_options* vopts;
+  struct timespec tspec;  // delay param, copy per thread
+};
+
+static int
+yielder(const void* vmarsh){
+  const struct marsh* m = vmarsh;
+  long tfilled = 0;
+  int iters = 0;
+  // less than this, and we exit almost immediately. more than this, and we
+  // run closer to twenty seconds. 11/50 it is, then. pixels are different.
+  const long threshold_painted = m->total * 11 / 50;
+  while(tfilled < threshold_painted && iters < MAXITER){
+//fprintf(stderr, "%d/%d tfilled: %ld thresh: %ld total: %ld\n", m->maxy, m->maxx, tfilled, threshold_painted, m->total);
+    int pfilled = 0;
+    do{
+      ++iters;
+      int x = rand() % m->maxx;
+      int y = rand() % m->maxy;
+      uint32_t pixel = 0;
+      if(ncvisual_at_yx(m->wmv, y, x, &pixel) < 0){
+        return -1;
+      }
+      if(ncpixel_a(pixel) != 0xff){ // don't do areas we've already done
+        continue;
+      }
+      if(ncpixel_g(pixel) < 0x80){ // only do land, which is whiter than blue
+        continue;
+      }
+      ncpixel_set_a(&pixel, 0xfe);
+      ncpixel_set_rgb8(&pixel, (rand() % 128) + 128, 0, ncpixel_b(pixel) / 4);
+      pfilled = ncvisual_polyfill_yx(m->wmv, y, x, pixel);
+      if(pfilled < 0){
+        return -1;
+      }
+      // it's possible that nothing changed (pfilled == 0), but render anyway
+      // so that it never looks like we locked up
+      DEMO_RENDER(m->nc);
+    }while(pfilled == 0);
+    tfilled += pfilled;
+    if(ncvisual_blit(m->nc, m->wmv, m->vopts) == NULL){
+      return -1;
+    }
+    if(tfilled > threshold_painted){
+      tfilled = threshold_painted; // don't allow printing of 100.1% etc
+    }
+    ncplane_printf_aligned(m->label, 0, NCALIGN_CENTER, "Yield: %3.1f%%", ((double)tfilled * 100) / threshold_painted);
+    DEMO_RENDER(m->nc);
+    demo_nanosleep(m->nc, &m->tspec);
+  }
+  return 0;
+}
+
 int yield_demo(struct notcurses* nc){
   if(!notcurses_canopen_images(nc)){
     return 0;
@@ -20,7 +82,7 @@ int yield_demo(struct notcurses* nc){
   const bool bitmaps = (notcurses_check_pixel_support(nc) > 0);
   struct ncplane_options nopts = {
     .y = 1,
-    .rows = dimy - 1 - bitmaps,
+    .rows = dimy - 1,
     .cols = dimx,
     .name = "wmap",
   };
@@ -44,14 +106,6 @@ int yield_demo(struct notcurses* nc){
     ncplane_destroy(vopts.n);
     return -1;
   }
-  struct timespec scaled;
-  const long total = maxy * maxx;
-  // less than this, and we exit almost immediately. more than this, and we
-  // run closer to twenty seconds. 11/50 it is, then. pixels are different.
-  const long threshold_painted = total * 11 / 50;
-  const int MAXITER = 1024;
-  timespec_div(&demodelay, 10, &scaled);
-  long tfilled = 0;
   struct ncplane_options labopts = {
     .y = 3,
     .x = NCALIGN_CENTER,
@@ -66,6 +120,18 @@ int yield_demo(struct notcurses* nc){
     ncplane_destroy(vopts.n);
     return -1;
   }
+  struct marsh marsh = {
+    .total = maxy * maxx,
+    .maxy = maxy,
+    .maxx = maxx,
+    .wmv = wmv,
+    .label = label,
+    .nc = nc,
+    .vopts = &vopts,
+  };
+  if(bitmaps){
+    timespec_div(&demodelay, 10, &marsh.tspec);
+  }
   uint64_t basechan = 0;
   ncchannels_set_bg_alpha(&basechan, NCALPHA_TRANSPARENT);
   ncchannels_set_fg_alpha(&basechan, NCALPHA_TRANSPARENT);
@@ -73,61 +139,16 @@ int yield_demo(struct notcurses* nc){
   ncplane_set_bg_alpha(label, NCALPHA_TRANSPARENT);
   ncplane_set_fg_rgb8(label, 0xff, 0xff, 0xff);
   ncplane_set_styles(label, NCSTYLE_BOLD);
-  ncplane_printf_aligned(label, 0, NCALIGN_CENTER, "Yield: %03.1f%%", ((double)tfilled * 100) / threshold_painted);
+  ncplane_printf_aligned(label, 0, NCALIGN_CENTER, "Yield: %03.1f%%", 0.0);
 
   DEMO_RENDER(nc);
   demo_nanosleep(nc, &demodelay);
 
-  int iters = 0;
-  while(tfilled < threshold_painted && iters < MAXITER){
-//fprintf(stderr, "%d/%d tfilled: %ld thresh: %ld total: %ld\n", maxy, maxx, tfilled, threshold_painted, total);
-    int pfilled = 0;
-    do{
-      ++iters;
-      int x = rand() % maxx;
-      int y = rand() % maxy;
-      uint32_t pixel = 0;
-      if(ncvisual_at_yx(wmv, y, x, &pixel) < 0){
-        ncvisual_destroy(wmv);
-        ncplane_destroy(vopts.n);
-        return -1;
-      }
-      if(ncpixel_a(pixel) != 0xff){ // don't do areas we've already done
-        continue;
-      }
-      if(ncpixel_g(pixel) < 0x80){ // only do land, which is whiter than blue
-        continue;
-      }
-      ncpixel_set_a(&pixel, 0xfe);
-      ncpixel_set_rgb8(&pixel, (rand() % 128) + 128, 0, ncpixel_b(pixel) / 4);
-      pfilled = ncvisual_polyfill_yx(wmv, y, x, pixel);
-      if(pfilled < 0){
-        ncvisual_destroy(wmv);
-        ncplane_destroy(vopts.n);
-        return -1;
-      }
-      // it's possible that nothing changed (pfilled == 0), but render anyway
-      // so that it never looks like we locked up
-      DEMO_RENDER(nc);
-    }while(pfilled == 0);
-    tfilled += pfilled;
-    if(ncvisual_blit(nc, wmv, &vopts) == NULL){
-      ncvisual_destroy(wmv);
-      ncplane_destroy(vopts.n);
-      return -1;
-    }
-    if(tfilled > threshold_painted){
-      tfilled = threshold_painted; // don't allow printing of 100.1% etc
-    }
-    ncplane_printf_aligned(label, 0, NCALIGN_CENTER, "Yield: %3.1f%%", ((double)tfilled * 100) / threshold_painted);
-    DEMO_RENDER(nc);
-    if(!bitmaps){
-      demo_nanosleep(nc, &scaled);
-    }
-  }
+  int ret = yielder(&marsh);
+
   ncplane_destroy(label);
   ncvisual_destroy(wmv);
   ncplane_destroy(vopts.n);
   ncplane_erase(std);
-  return 0;
+  return ret;
 }