2 files changed, 2 insertions, 2 deletions
diff --git a/Object.c b/Object.c
index 9ac2be67..982f7bda 100644
--- a/Object.c
+++ b/Object.c
@@ -14,7 +14,7 @@ ObjectClass Object_class = {
 
 #ifndef NDEBUG
 
-bool Object_isA(Object* o, const ObjectClass* klass) {
+bool Object_isA(const Object* o, const ObjectClass* klass) {
    if (!o)
       return false;
    const ObjectClass* type = o->klass;
diff --git a/Object.h b/Object.h
index 462797c2..ba213c89 100644
--- a/Object.h
+++ b/Object.h
@@ -50,7 +50,7 @@ extern ObjectClass Object_class;
 
 #ifndef NDEBUG
 
-bool Object_isA(Object* o, const ObjectClass* klass);
+bool Object_isA(const Object* o, const ObjectClass* klass);
 
 #endif /* NDEBUG */