diff --git a/python/lammps/core.py b/python/lammps/core.py
index 5e51a7bba0..fcd5c76ad5 100644
--- a/python/lammps/core.py
+++ b/python/lammps/core.py
@@ -99,7 +99,7 @@ class lammps(object):
     # load a shared object.
 
     try:
-      if ptr: self.lib = CDLL("",RTLD_GLOBAL)
+      if ptr is not None: self.lib = CDLL("",RTLD_GLOBAL)
     except OSError:
       self.lib = None
 
@@ -329,7 +329,7 @@ class lammps(object):
     #   ptr is the desired instance of LAMMPS
     #   just convert it to ctypes ptr and store in self.lmp
 
-    if not ptr:
+    if ptr is None:
 
       # with mpi4py v2+, we can pass MPI communicators to LAMMPS
       # need to adjust for type of MPI communicator object
@@ -338,7 +338,7 @@ class lammps(object):
         from mpi4py import MPI
         self.MPI = MPI
 
-      if comm:
+      if comm is not None:
         if not self.has_mpi_support:
           raise Exception('LAMMPS not compiled with real MPI library')
         if not self.has_mpi4py:
@@ -354,7 +354,7 @@ class lammps(object):
 
         narg = 0
         cargs = None
-        if cmdargs:
+        if cmdargs is not None:
           cmdargs.insert(0,"lammps")
           narg = len(cmdargs)
           for i in range(narg):
@@ -376,7 +376,7 @@ class lammps(object):
         if self.has_mpi4py and self.has_mpi_support:
           self.comm = self.MPI.COMM_WORLD
         self.opened = 1
-        if cmdargs:
+        if cmdargs is not None:
           cmdargs.insert(0,"lammps")
           narg = len(cmdargs)
           for i in range(narg):
diff --git a/python/lammps/pylammps.py b/python/lammps/pylammps.py
index a6e3578aef..abd4d6da98 100644
--- a/python/lammps/pylammps.py
+++ b/python/lammps/pylammps.py
@@ -854,30 +854,30 @@ class IPyLammps(PyLammps):
     """
     cmd_args = [group, "image", filename, color, diameter]
 
-    if size:
+    if size is not None:
       width = size[0]
       height = size[1]
       cmd_args += ["size", width, height]
 
-    if view:
+    if view is not None:
       theta = view[0]
       phi = view[1]
       cmd_args += ["view", theta, phi]
 
-    if center:
+    if center is not None:
       flag = center[0]
       Cx = center[1]
       Cy = center[2]
       Cz = center[3]
       cmd_args += ["center", flag, Cx, Cy, Cz]
 
-    if up:
+    if up is not None:
       Ux = up[0]
       Uy = up[1]
       Uz = up[2]
       cmd_args += ["up", Ux, Uy, Uz]
 
-    if zoom:
+    if zoom is not None:
       cmd_args += ["zoom", zoom]
 
     cmd_args.append("modify backcolor " + background_color)