diff --git a/src/test/app/LoanBroker_test.cpp b/src/test/app/LoanBroker_test.cpp
index d2a8a3656d..6f9cffbf1d 100644
--- a/src/test/app/LoanBroker_test.cpp
+++ b/src/test/app/LoanBroker_test.cpp
@@ -1015,6 +1015,24 @@ class LoanBroker_test : public beast::unit_test::suite
                 sig(sfCounterpartySignature, alice),
                 fee(env.current()->fees().base * 2));
 
+            // preflight: temINVALID (empty broker id)
+            {
+                auto jv = del(alice, brokerKeylet.key);
+                jv[sfLoanBrokerID] = "";
+                env(jv, ter(temINVALID));
+            }
+            // preflight: temINVALID (zero broker id)
+            {
+                // needs a flag to distinguish the parsed STTx from the prior
+                // test
+                auto jv = del(alice, uint256{}, tfFullyCanonicalSig);
+                BEAST_EXPECT(
+                    jv[sfLoanBrokerID] ==
+                    "0000000000000000000000000000000000000000000000000000000000"
+                    "000000");
+                env(jv, ter(temINVALID));
+            }
+
             // preclaim: tecHAS_OBLIGATIONS
             env(del(alice, brokerKeylet.key), ter(tecHAS_OBLIGATIONS));
         }
diff --git a/src/xrpld/app/tx/detail/LoanBrokerDelete.cpp b/src/xrpld/app/tx/detail/LoanBrokerDelete.cpp
index 90703fa5b9..07e05ec073 100644
--- a/src/xrpld/app/tx/detail/LoanBrokerDelete.cpp
+++ b/src/xrpld/app/tx/detail/LoanBrokerDelete.cpp
@@ -32,6 +32,9 @@ LoanBrokerDelete::checkExtraFeatures(PreflightContext const& ctx)
 NotTEC
 LoanBrokerDelete::preflight(PreflightContext const& ctx)
 {
+    if (ctx.tx[sfLoanBrokerID] == beast::zero)
+        return temINVALID;
+
     return tesSUCCESS;
 }