diff --git a/src/layouts.jl b/src/layouts.jl
index 9440da31..90892adf 100644
--- a/src/layouts.jl
+++ b/src/layouts.jl
@@ -479,6 +479,8 @@ function build_layout(layout::GridLayout, n::Integer)
             append!(subplots, sps)
             merge!(spmap, m)
             i += length(sps)
+        elseif isa(l, Subplot)
+            error("Subplot exists. Cannot re-use existing layout.  Please make a new one.")
         end
         i >= n && break  # only add n subplots
     end
diff --git a/src/utils.jl b/src/utils.jl
index 1fdab38f..a0009d64 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -152,7 +152,7 @@ function iter_segments(args...)
 end
 
 # helpers to figure out if there are NaN values in a list of array types
-anynan(i::Int, args...) = any(a -> isnan(cycle(a,i)), args)
+anynan(i::Int, args...) = any(a -> !isfinite(cycle(a,i)), args)
 anynan(istart::Int, iend::Int, args...) = any(i -> anynan(i, args...), istart:iend)
 allnan(istart::Int, iend::Int, args...) = all(i -> anynan(i, args...), istart:iend)