diff --git a/src/optics/aerosol_optics.jl b/src/optics/aerosol_optics.jl
index 6f0945d98..0dc48b9ed 100644
--- a/src/optics/aerosol_optics.jl
+++ b/src/optics/aerosol_optics.jl
@@ -282,6 +282,7 @@ function locate_merra_size_bin(size_bin_limits, aerosize)
                 bin = ibin
                 break
             end
+            bin = nbins
         end
     end
     return bin