diff --git a/src/goto-symex/slice.cpp b/src/goto-symex/slice.cpp
index 565f9e1b24b..da96060640f 100644
--- a/src/goto-symex/slice.cpp
+++ b/src/goto-symex/slice.cpp
@@ -266,7 +266,7 @@ void simple_slice(symex_target_equationt &equation)
 void revert_slice(symex_target_equationt &equation)
 {
   // set ignore to false
-  for(auto step : equation.SSA_steps)
+  for(auto &step : equation.SSA_steps)
   {
     step.ignore = false;
   }