diff --git a/src/plugins/e-acsl/translate.ml b/src/plugins/e-acsl/translate.ml
index e4247eea1849c3589e849b01133fdcd083a2a8cd..97da08d3b5462a475d9ad1a0973da7d23ee08a82 100644
--- a/src/plugins/e-acsl/translate.ml
+++ b/src/plugins/e-acsl/translate.ml
@@ -997,6 +997,7 @@ let translate_pre_code_annotation kf stmt env annot =
       then not_yet env "allocation"
       else env
     | APragma _ -> not_yet env "pragma"
+    | AExtended _ -> env (* never translate extensions. *)
   in
   handle_error convert env
 
@@ -1008,7 +1009,8 @@ let translate_post_code_annotation kf stmt env annot =
     | AVariant _
     | AAssigns _
     | AAllocation _
-    | APragma _ -> env
+    | APragma _
+    | AExtended _ -> env
   in
   handle_error convert env