diff --git a/genobuilder.py b/genobuilder.py
index 6fd03a2..c48a7f1 100644
--- a/genobuilder.py
+++ b/genobuilder.py
@@ -154,8 +154,8 @@ def sim_source(self, s):
             )
         self._sim_source = s
 
-        
-    def simulate_msprime(self, params, random=False, gauss=False):
+
+    def simulate_msprime(self, params, randomize=False, gauss=False):
 
         """Simulate demographic data, returning a tensor with n_reps number
         of genotype matrices"""