Index: lib/matrix/lup_decomposition.rb
===================================================================
--- lib/matrix/lup_decomposition.rb	(revision 38581)
+++ lib/matrix/lup_decomposition.rb	(working copy)
@@ -77,7 +77,7 @@
 
     def det
       if (@row_count != @column_count)
-        Matrix.Raise Matrix::ErrDimensionMismatch unless square?
+        Matrix.Raise Matrix::ErrDimensionMismatch
       end
       d = @pivot_sign
       @column_count.times do |j|