diff --git a/gprMax/input_cmds_multiuse.py b/gprMax/input_cmds_multiuse.py
index 487c75b1..a1b84c26 100644
--- a/gprMax/input_cmds_multiuse.py
+++ b/gprMax/input_cmds_multiuse.py
@@ -571,6 +571,8 @@ def process_multicmds(multicmds, G):
                 raise CmdInputError("'" + cmdname + ': ' + ' '.join(tmp) + "'" + ' the lower coordinates should be less than the upper coordinates')
             if dx < 0 or dy < 0 or dz < 0:
                 raise CmdInputError("'" + cmdname + ': ' + ' '.join(tmp) + "'" + ' the step size should not be less than zero')
+            if dx > G.nx or dy > G.ny or dz > G.nz:
+                raise CmdInputError("'" + cmdname + ': ' + ' '.join(tmp) + "'" + ' the step size should be less than the domain size')
             if dx < G.dx or dy < G.dy or dz < G.dz:
                 raise CmdInputError("'" + cmdname + ': ' + ' '.join(tmp) + "'" + ' the step size should not be less than the spatial discretisation')
             if tmp[10].lower() != 'n' and tmp[10].lower() != 'f':