diff --git a/shell_encryption/rns/rns_galois_key.h b/shell_encryption/rns/rns_galois_key.h
index 96f025f..d4a3f8d 100644
--- a/shell_encryption/rns/rns_galois_key.h
+++ b/shell_encryption/rns/rns_galois_key.h
@@ -230,7 +230,7 @@ class RnsGaloisKey {
     return key_bs_;
   }
 
-  const RnsGadget<ModularInt>* Gadget() { return gadget_; }
+  const RnsGadget<ModularInt>* Gadget() const { return gadget_; }
 
   int Dimension() const { return key_as_.size(); }
 
diff --git a/shell_encryption/rns/rns_relinearization_key.h b/shell_encryption/rns/rns_relinearization_key.h
index 0afb2f2..dd79b32 100644
--- a/shell_encryption/rns/rns_relinearization_key.h
+++ b/shell_encryption/rns/rns_relinearization_key.h
@@ -112,7 +112,7 @@ class RnsRelinKey {
     return key_bs_;
   }
 
-  const RnsGadget<ModularInt>* Gadget() { return gadget_; }
+  const RnsGadget<ModularInt>* Gadget() const { return gadget_; }
 
   int Dimension() const { return gadget_->Dimension(); }