diff --git a/modules/Layout.js b/modules/Layout.js
index 521b191b6..bfb13a561 100644
--- a/modules/Layout.js
+++ b/modules/Layout.js
@@ -329,14 +329,14 @@ Layout.prototype.update = function() {
       l.c.forEach(updateMin);
       l._h = l.c.reduce((a,b)=>Math.max(a,b._h+(b.pad<<1)),0);
       l._w = l.c.reduce((a,b)=>a+b._w+(b.pad<<1),0);
-      if (l.c.some(c=>c.fillx)) l.fillx = 1;
-      if (l.c.some(c=>c.filly)) l.filly = 1;
+      if (l.fillx == null && l.c.some(c=>c.fillx)) l.fillx = 1;
+      if (l.filly == null && l.c.some(c=>c.filly)) l.filly = 1;
     }, "v": function(l) {
       l.c.forEach(updateMin);
       l._h = l.c.reduce((a,b)=>a+b._h+(b.pad<<1),0);
       l._w = l.c.reduce((a,b)=>Math.max(a,b._w+(b.pad<<1)),0);
-      if (l.c.some(c=>c.fillx)) l.fillx = 1;
-      if (l.c.some(c=>c.filly)) l.filly = 1;
+      if (l.fillx == null && l.c.some(c=>c.fillx)) l.fillx = 1;
+      if (l.filly == null && l.c.some(c=>c.filly)) l.filly = 1;
     }
   };
   updateMin(l);
diff --git a/tests/Layout/tests/filly_issue820.bmp b/tests/Layout/tests/filly_issue820.bmp
new file mode 100644
index 000000000..886ba97d8
Binary files /dev/null and b/tests/Layout/tests/filly_issue820.bmp differ
diff --git a/tests/Layout/tests/filly_issue820.js b/tests/Layout/tests/filly_issue820.js
new file mode 100644
index 000000000..4b813fadf
--- /dev/null
+++ b/tests/Layout/tests/filly_issue820.js
@@ -0,0 +1,9 @@
+g.clear();
+var layout = new Layout({type:"h", filly: 0, c: [
+  {type: "txt", font: "50%", label: "A"},
+  {type:"v", c: [
+    {type: "txt", font: "10%", label: "B"},
+    {filly: 1},
+    {type: "txt", font: "10%", label: "C"},
+  ]},
+]});