diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -1805,11 +1805,12 @@
                  }},
                 {RPCResult::Type::STR_HEX, "lastblock",
                  "The hash of the block (target_confirmations-1) from the best "
-                 "block on the main chain. This is typically used to feed back "
-                 "into listsinceblock the next time you call it. So you would "
-                 "generally use a target_confirmations of say 6, so you will "
-                 "be continually re-notified of transactions until they've "
-                 "reached 6 confirmations plus any new ones"},
+                 "block on the main chain, or the genesis hash if the "
+                 "referenced block does not exist yet. This is typically used "
+                 "to feed back into listsinceblock the next time you call it. "
+                 "So you would generally use a target_confirmations of say 6, "
+                 "so you will be continually re-notified of transactions until "
+                 "they've reached 6 confirmations plus any new ones"},
             }},
         RPCExamples{HelpExampleCli("listsinceblock", "") +
                     HelpExampleCli("listsinceblock",
@@ -1910,6 +1911,8 @@
     }
 
     BlockHash lastblock;
+    target_confirms =
+        std::min(target_confirms, wallet.GetLastBlockHeight() + 1);
     CHECK_NONFATAL(wallet.chain().findAncestorByHeight(
         wallet.GetLastBlockHash(),
         wallet.GetLastBlockHeight() + 1 - target_confirms,
diff --git a/test/functional/wallet_listsinceblock.py b/test/functional/wallet_listsinceblock.py
--- a/test/functional/wallet_listsinceblock.py
+++ b/test/functional/wallet_listsinceblock.py
@@ -34,6 +34,7 @@
         self.test_reorg()
         self.test_double_spend()
         self.test_double_send()
+        self.test_targetconfirmations()
 
     def test_no_blockhash(self):
         self.log.info("Test no blockhash")
@@ -73,6 +74,27 @@
         assert_raises_rpc_error(-8, "blockhash must be hexadecimal string (not 'Z000000000000000000000000000000000000000000000000000000000000000')", self.nodes[0].listsinceblock,
                                 "Z000000000000000000000000000000000000000000000000000000000000000")
 
+    def test_targetconfirmations(self):
+        '''
+        This tests when the value of target_confirmations exceeds the number of
+        blocks in the main chain. In this case, the genesis block hash should be
+        given for the `lastblock` property. If target_confirmations is < 1, then
+        a -8 invalid parameter error is thrown.
+        '''
+        self.log.info("Test target_confirmations")
+        blockhash, = self.nodes[2].generate(1)
+        blockheight = self.nodes[2].getblockheader(blockhash)['height']
+        self.sync_all()
+
+        assert_equal(
+            self.nodes[0].getblockhash(0),
+            self.nodes[0].listsinceblock(blockhash, blockheight + 1)['lastblock'])
+        assert_equal(
+            self.nodes[0].getblockhash(0),
+            self.nodes[0].listsinceblock(blockhash, blockheight + 1000)['lastblock'])
+        assert_raises_rpc_error(-8, "Invalid parameter",
+                                self.nodes[0].listsinceblock, blockhash, 0)
+
     def test_reorg(self):
         '''
         `listsinceblock` did not behave correctly when handed a block that was