diff --git a/pymath/calculus/random_expression.py b/pymath/calculus/random_expression.py
index f4c7849..2a84c46 100644
--- a/pymath/calculus/random_expression.py
+++ b/pymath/calculus/random_expression.py
@@ -6,6 +6,9 @@ import re
 import pyparsing
 from .generic import flatten_list
 
+# Below import are needed for conditions in varia generation.
+from .arithmetic import gcd
+
 
 def random_str(form, conditions=[], val_min=-10, val_max=10):
     """ Create a random string using RdExpression class  """