diff --git a/src/shape_functions.jl b/src/shape_functions.jl
index 1b858d7..f28250e 100644
--- a/src/shape_functions.jl
+++ b/src/shape_functions.jl
@@ -4,6 +4,7 @@ end
 
 
 function C2D4(xx)
+     θ = 1
      chi = xx[1]
      eta = xx[2]
      return = [(1 - chi) * (1 - eta),