diff --git a/gprMax/waveforms.py b/gprMax/waveforms.py
index 886a8a32..ffff0980 100644
--- a/gprMax/waveforms.py
+++ b/gprMax/waveforms.py
@@ -44,15 +44,17 @@ class Waveform:
             waveform (float): Calculated value for waveform.
         """
         
+        # Coefficients for certain waveforms
         if self.type == 'gaussiandotdot' or self.type == 'gaussiandotdotnorm' or self.type == 'ricker':
             chi = np.sqrt(2) / self.freq
             zeta = np.pi * np.pi * self.freq * self.freq
             delay = time - chi
-        else:
+        elif self.type == 'gaussian' or self.type == 'gaussiandot' or self.type == 'gaussiandotnorm':
             chi = 1 / self.freq
             zeta = 2 * np.pi * np.pi * self.freq * self.freq
             delay = time - chi
 
+        # Waveforms
         if self.type == 'gaussian':
             waveform = np.exp(-zeta * delay * delay)