diff --git a/treegp/two_pcf.py b/treegp/two_pcf.py
index b201222..eb3ebfc 100644
--- a/treegp/two_pcf.py
+++ b/treegp/two_pcf.py
@@ -145,7 +145,7 @@ def chi2(self, param):
                     self.residuals.reshape((len(model), 1))
                 )
 
-        return self.chi2_value
+        return self.chi2_value[0]
 
     def _minimize_minuit(self, p0=[3000.0, 0.2, 0.2]):
         """