diff --git a/src/equilibrium.f90 b/src/equilibrium.f90
index 9d74a73..d3506c2 100644
--- a/src/equilibrium.f90
+++ b/src/equilibrium.f90
@@ -1195,7 +1195,13 @@ contains
 
       case (EQ_EQDSK_FULL, EQ_EQDSK_PARTIAL)
         ! Numerical data
-        fq = q_spline%eval(psin)
+        if (psin < 1) then
+          fq = q_spline%eval(psin)
+        else
+          ! q is undefined or infinite
+          fq = 0
+        end if
+
     end select
   end function fq