diff --git a/pySD/initsuperdropsbinary_src/read_initsuperdrops.py b/pySD/initsuperdropsbinary_src/read_initsuperdrops.py
index 63635bf4..34dfc47b 100644
--- a/pySD/initsuperdropsbinary_src/read_initsuperdrops.py
+++ b/pySD/initsuperdropsbinary_src/read_initsuperdrops.py
@@ -403,7 +403,7 @@ def plot_initGBxs_dropletmasses(
         gbxidxs = np.unique(attrs.sdgbxindex)
         savename = binpath + "initallGBxs_dropletmasses" + savelabel + ".png"
     else:
-        gbxidxs = gbxs2plt
+        gbxidxs = [int(g) for g in gbxs2plt]
         savename = binpath + "initGBxs_dropletmasses" + savelabel + ".png"
 
     fig, axs, lines = plot_massdistribs(