diff --git a/src/kernel/declaration.cpp b/src/kernel/declaration.cpp
index c831406f38..50860e79f8 100644
--- a/src/kernel/declaration.cpp
+++ b/src/kernel/declaration.cpp
@@ -262,7 +262,7 @@ bool constant_info::is_unsafe() const {
     case constant_info_kind::Axiom:       return to_axiom_val().is_unsafe();
     case constant_info_kind::Definition:  return to_definition_val().is_unsafe();
     case constant_info_kind::Theorem:     return false;
-    case constant_info_kind::Opaque:     return false;
+    case constant_info_kind::Opaque:      return to_opaque_val().is_unsafe();
     case constant_info_kind::Quot:        return false;
     case constant_info_kind::Inductive:   return to_inductive_val().is_unsafe();
     case constant_info_kind::Constructor: return to_constructor_val().is_unsafe();
diff --git a/stage0/src/kernel/declaration.cpp b/stage0/src/kernel/declaration.cpp
index c831406f38..50860e79f8 100644
--- a/stage0/src/kernel/declaration.cpp
+++ b/stage0/src/kernel/declaration.cpp
@@ -262,7 +262,7 @@ bool constant_info::is_unsafe() const {
     case constant_info_kind::Axiom:       return to_axiom_val().is_unsafe();
     case constant_info_kind::Definition:  return to_definition_val().is_unsafe();
     case constant_info_kind::Theorem:     return false;
-    case constant_info_kind::Opaque:     return false;
+    case constant_info_kind::Opaque:      return to_opaque_val().is_unsafe();
     case constant_info_kind::Quot:        return false;
     case constant_info_kind::Inductive:   return to_inductive_val().is_unsafe();
     case constant_info_kind::Constructor: return to_constructor_val().is_unsafe();