diff --git a/wrappers/Python/CoolProp/CoolProp.pyx b/wrappers/Python/CoolProp/CoolProp.pyx
index c2cff3ab..c719621a 100644
--- a/wrappers/Python/CoolProp/CoolProp.pyx
+++ b/wrappers/Python/CoolProp/CoolProp.pyx
@@ -185,6 +185,14 @@ cpdef PropsSI(in1, in2, in3 = None, in4 = None, in5 = None, in6 = None, in7 = No
         if iterable(in3) and iterable(in5):
             # This version takes iterables
             return _PropsSII(in1, in2, in3, in4, in5, in6)
+        elif iterable(in3) and not(iterable(in5)):
+            i5 = [in5]*len(in3)
+            # This version takes iterables
+            return _PropsSII(in1, in2, in3, in4, i5, in6)
+        elif iterable(in5) and not(iterable(in3)):
+            i3 = [in3]*len(in5)
+            # This version takes iterables
+            return _PropsSII(in1, in2, i3, in4, in5, in6)
         else:
             # This version takes doubles
             val = _PropsSI(in1, in2, in3, in4, in5, in6)