diff --git a/fenicsR13/solver.py b/fenicsR13/solver.py
index 357d8494e8f7ad4bb2db960b0d427e9fe07a7d80..536cf581f660285b758c8914e6d91554330fa9e7 100644
--- a/fenicsR13/solver.py
+++ b/fenicsR13/solver.py
@@ -1410,7 +1410,7 @@ class Solver:
         print("Write {}".format(A_name))
         np.savetxt(A_name, df.assemble(self.form_lhs).array())
         print("Write {}".format(b_name))
-        np.savetxt(b_name,df.assemble(self.form_rhs))
+        np.savetxt(b_name, df.assemble(self.form_rhs))
 
     def __write_xdmf(self, name, field, write_pdf):
         """