diff --git a/tools/plot_Ascan.py b/tools/plot_Ascan.py
index 71fcbc0b..64c5de02 100644
--- a/tools/plot_Ascan.py
+++ b/tools/plot_Ascan.py
@@ -30,7 +30,7 @@ from gprMax.receivers import Rx
 # Parse command line arguments
 parser = argparse.ArgumentParser(description='Plots electric and magnetic fields and currents from all receiver points in the given output file. Each receiver point is plotted in a new figure window.', usage='cd gprMax; python -m tools.plot_Ascan outputfile')
 parser.add_argument('outputfile', help='name of output file including path')
-parser.add_argument('--outputs', help='outputs to be plotted (Ex, Ey, Ez, Hx, Hy, Hz, Ix, Iy, Iz)', default=Rx.availableoutputs, nargs='+')
+parser.add_argument('--outputs', help='outputs to be plotted', choices='Ex, Ey, Ez, Hx, Hy, Hz, Ix, Iy, Iz', default=Rx.availableoutputs, nargs='+')
 parser.add_argument('-fft', action='store_true', default=False, help='plot FFT (single output must be specified)')
 args = parser.parse_args()
 
diff --git a/tools/plot_Bscan.py b/tools/plot_Bscan.py
index bf97b37b..5e75b5b4 100644
--- a/tools/plot_Bscan.py
+++ b/tools/plot_Bscan.py
@@ -28,7 +28,7 @@ from gprMax.exceptions import CmdInputError
 # Parse command line arguments
 parser = argparse.ArgumentParser(description='Plots a B-scan image.', usage='cd gprMax; python -m tools.plot_Bscan outputfile output')
 parser.add_argument('outputfile', help='name of output file including path')
-parser.add_argument('output', help='name of output component to be plotted (Ex, Ey, Ez, Hx, Hy, Hz, Ix, Iy or Iz)')
+parser.add_argument('output', help='name of output component to be plotted', choices='Ex, Ey, Ez, Hx, Hy, Hz, Ix, Iy or Iz')
 args = parser.parse_args()
 
 # Open output file and read some attributes