diff --git a/parallel.py b/parallel.py
index eb15e10..5da4329 100644
--- a/parallel.py
+++ b/parallel.py
@@ -521,7 +521,7 @@ class PPP:
         return
 
     def set_noslip_bc(self,axis,wall):
-        '''Applies symmetry: [u,v,w](x,-y,z) -> [-u,-v,-w](x,y,z)
+        '''Applies symmetry: [u,v,w](x,-y,z) -> [-u,v,-w](x,y,z)
            The boundary conditions are only applied to fields which have already been loaded!'''
         if self.periodicity[axis]:
             return
@@ -536,7 +536,10 @@ class PPP:
             sl = [1,1,1]
             sl[axis] = iwall
             sl = tuple(sl)
-            self.symmetries[key][sl] = -1
+            if key==keyu[axis]:
+                self.symmetries[key][sl] = 1
+            else:
+                self.symmetries[key][sl] = -1
             self.impose_boundary_conditions(key)
         return