diff --git a/src/dump_image.cpp b/src/dump_image.cpp
index eedfb89992..0e5f57be6b 100644
--- a/src/dump_image.cpp
+++ b/src/dump_image.cpp
@@ -1345,7 +1345,7 @@ int DumpImage::modify_param(int narg, char **arg)
     if (atom->nbondtypes == 0)
       error->all(FLERR,"Dump modify bdiam not allowed with no bond types");
     int nlo,nhi;
-    force->bounds(FLERR,arg[1],atom->ntypes,nlo,nhi);
+    force->bounds(FLERR,arg[1],atom->nbondtypes,nlo,nhi);
     double diam = force->numeric(FLERR,arg[2]);
     if (diam <= 0.0) error->all(FLERR,"Illegal dump_modify command");
     for (int i = nlo; i <= nhi; i++) bdiamtype[i] = diam;