diff --git a/src/ripple/app/hook/Guard.h b/src/ripple/app/hook/Guard.h
index 16b11b037..7e24de452 100644
--- a/src/ripple/app/hook/Guard.h
+++ b/src/ripple/app/hook/Guard.h
@@ -1109,8 +1109,11 @@ validateGuards(
                 {
                     for (auto const& [import_idx, api_name] : usage->second)
                     {
-                        auto const& api_signature =  
-                            hook_api::import_whitelist.find(api_name)->second;
+
+                        auto const& api_signature = 
+                            hook_api::import_whitelist.find(api_name) != hook_api::import_whitelist.end()
+                                ? hook_api::import_whitelist.find(api_name)->second 
+                                : hook_api::import_whitelist_1.find(api_name)->second;
 
                         if (!first_signature)
                         {
diff --git a/src/ripple/app/hook/impl/applyHook.cpp b/src/ripple/app/hook/impl/applyHook.cpp
index dfbbb23cc..135a4af55 100644
--- a/src/ripple/app/hook/impl/applyHook.cpp
+++ b/src/ripple/app/hook/impl/applyHook.cpp
@@ -5521,7 +5521,7 @@ DEFINE_HOOK_FUNCTION(
     if (slot_into_tx > hook_api::max_slots || slot_into_meta > hook_api::max_slots)
         return INVALID_ARGUMENT;
 
-    size_t free_count = hookCtx.slot_free.size();
+    size_t free_count = hook_api::max_slots - hookCtx.slot.size();
 
     size_t needed_count = 
         slot_into_tx == 0 && slot_into_meta == 0 ? 2 : slot_into_tx != 0 && slot_into_meta != 0 ? 0 : 1; 
diff --git a/src/ripple/app/tx/impl/Import.cpp b/src/ripple/app/tx/impl/Import.cpp
index d0a16ad29..856eb5218 100644
--- a/src/ripple/app/tx/impl/Import.cpp
+++ b/src/ripple/app/tx/impl/Import.cpp
@@ -280,19 +280,6 @@ Import::preflight(PreflightContext const& ctx)
         return telWRONG_NETWORK;
     }
 
-/*
-    // ensure the inner txn is an accountset or signerlistset
-    auto const tt = stpTrans->getTxnType();
-
-    if (tt != ttACCOUNT_SET && tt != ttSIGNER_LIST_SET && tt != ttREGULAR_KEY_SET)
-    {
-        JLOG(ctx.j.warn())
-            << "Import: inner txn must be an AccountSet, SetRegularKey or SignerListSet transaction. "
-            << tx.getTransactionID();
-        return temMALFORMED;
-    }
-*/
-
     // check if the inner transaction is signed using the same keying as the outer txn
     {
         auto outer = tx.getSigningPubKey();
@@ -838,20 +825,6 @@ Import::preflight(PreflightContext const& ctx)
         return temMALFORMED;
     }
 
-    /*
-     * RH TODO: put this in preclaim, place sequence on an unowned object
-    else if (sequence < listCollection.current.sequence)
-    {
-        return ListDisposition::stale;
-    }
-    else if (sequence == listCollection.current.sequence)
-        return ListDisposition::same_sequence;
-    */
-    //
-    // finally in preclaim check the sfImportSequence field on the account
-    // if it is less than the Account Sequence in the xpop then mint and
-    // update sfImportSequence
-
     // Duplicate / Sanity
     if (!stpTrans->isFieldPresent(sfSequence) ||
         !stpTrans->isFieldPresent(sfFee) ||
@@ -862,11 +835,18 @@ Import::preflight(PreflightContext const& ctx)
             << tx.getTransactionID();
         return temMALFORMED;
     }
+
+    if (stpTrans->getFieldAmount(sfFee) < beast::zero)
+    {
+        JLOG(ctx.j.warn())
+            << "Import: xpop contained negative fee. "
+            << tx.getTransactionID();
+        return temMALFORMED;
+    }
+
     return preflight2(ctx);
 }
 
-// RH TODO: manifest serials should be kept on chain
-
 TER
 Import::preclaim(PreclaimContext const& ctx)
 {
diff --git a/src/ripple/app/tx/impl/InvariantCheck.cpp b/src/ripple/app/tx/impl/InvariantCheck.cpp
index 2202fd288..f67715989 100644
--- a/src/ripple/app/tx/impl/InvariantCheck.cpp
+++ b/src/ripple/app/tx/impl/InvariantCheck.cpp
@@ -196,7 +196,13 @@ XRPNotCreated::finalize(
             << " drops_: " << drops_ 
             << " dropsAdded - fee.drops(): " << dropsAdded - fee.drops();
 
-        return (drops_ == dropsAdded.drops() - fee.drops());
+        int64_t drops = dropsAdded.drops() - fee.drops();
+
+        // catch any overflow or funny business
+        if (drops > dropsAdded.drops() || drops > fee.drops())
+            return false;
+
+        return drops_ == drops;
     }