diff --git a/SU2_PY/OptimalPropeller.py b/SU2_PY/OptimalPropeller.py
index c9ae32113286..571e3eb817e3 100644
--- a/SU2_PY/OptimalPropeller.py
+++ b/SU2_PY/OptimalPropeller.py
@@ -171,6 +171,7 @@ def write_external_file(CTrs, CPrs):
 rs_hub = rhub / R
 
 # Computation of the non-dimensional radial stations.
+i_hub = 0
 for i in range(1, stations + 1):
     r[i - 1] = i / float(stations)
     if r[i - 1] <= rs_hub: