@@ 221,6 221,18 @@ fn simplex_reduce(this: &mut Simplex, other: &Simplex) {
         }
     }
 
+    while our_i < our_last {
+        buf[buffer_i] = this.faces[our_i];
+        our_i += 1;
+        buffer_i += 1;
+    }
+
+    while their_i < their_last {
+        buf[buffer_i] = this.faces[their_i];
+        their_i += 1;
+        buffer_i += 1;
+    }
+
     if fastpath {
         this.faces.reserve(num_inds);
         this.faces.clear();