diff --git a/stardis/opacities/voigt.py b/stardis/opacities/voigt.py
index 7601510c..c1795e7a 100644
--- a/stardis/opacities/voigt.py
+++ b/stardis/opacities/voigt.py
@@ -25,6 +25,7 @@ def _faddeeva(z):
     -------
     w : complex
     """
+    z = complex(z)
     x = float(z.real)
     y = float(z.imag)
     t = y - 1j * x