diff --git a/src/libaevol/world/ExpManager.h b/src/libaevol/world/ExpManager.h
index b66515150500372f458615e74745dfcafb03cfd2..d8ea9ba6a7fb5a11ca9ede15c915bbacb63f88f7 100644
--- a/src/libaevol/world/ExpManager.h
+++ b/src/libaevol/world/ExpManager.h
@@ -223,7 +223,7 @@ class ExpManager : public Observer {
 
     bool first_gen = true;
 
-    bool check_simd_ = true;
+    bool check_simd_ = false;
 
         //wether you stop the simulation based on the age of mrca or not
         bool with_mrca_ = false;