diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -979,7 +979,7 @@
         return m_pool_key_to_index;
     }
     /** Does the wallet have at least min_keys in the keypool? */
-    bool HasUnusedKeys(int min_keys) const;
+    bool HasUnusedKeys(size_t min_keys) const;
 
     std::set<std::set<CTxDestination>> GetAddressGroupings();
     std::map<CTxDestination, Amount> GetAddressBalances();
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3778,7 +3778,7 @@
     }
 }
 
-bool CWallet::HasUnusedKeys(int min_keys) const {
+bool CWallet::HasUnusedKeys(size_t min_keys) const {
     return setExternalKeyPool.size() >= min_keys &&
            (setInternalKeyPool.size() >= min_keys ||
             !CanSupportFeature(FEATURE_HD_SPLIT));