diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 16055175fb..28d075aaba 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1377,7 +1377,7 @@ CoinStatsHashType ParseHashType(const std::string& hash_type_input)
     } else if (hash_type_input == "none") {
         return CoinStatsHashType::NONE;
     } else {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("%s is not a valid hash_type", hash_type_input));
+        throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("'%s' is not a valid hash_type", hash_type_input));
     }
 }
 
@@ -2520,7 +2520,7 @@ static RPCHelpMan getblockstats()
     for (const std::string& stat : stats) {
         const UniValue& value = ret_all[stat];
         if (value.isNull()) {
-            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid selected statistic %s", stat));
+            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid selected statistic '%s'", stat));
         }
         ret.pushKV(stat, value);
     }
diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
index 3b02da632f..3741a1b9a9 100644
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -255,7 +255,7 @@ CPubKey AddrToPubKey(const FillableSigningProvider& keystore, const std::string&
     }
     const PKHash *pkhash = std::get_if<PKHash>(&dest);
     if (!pkhash) {
-        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("%s does not refer to a key", addr_in));
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("'%s' does not refer to a key", addr_in));
     }
     CPubKey vchPubKey;
     if (!keystore.GetPubKey(ToKeyID(*pkhash), vchPubKey)) {
diff --git a/test/functional/rpc_blockchain.py b/test/functional/rpc_blockchain.py
index fedeb1f3d8..fb1c019769 100755
--- a/test/functional/rpc_blockchain.py
+++ b/test/functional/rpc_blockchain.py
@@ -299,7 +299,7 @@ class BlockchainTest(BitcoinTestFramework):
             assert 'muhash' not in r
 
         # Unknown hash_type raises an error
-        assert_raises_rpc_error(-8, "foohash is not a valid hash_type", node.gettxoutsetinfo, "foohash")
+        assert_raises_rpc_error(-8, "'foo hash' is not a valid hash_type", node.gettxoutsetinfo, "foo hash")
 
     def _test_getblockheader(self):
         self.log.info("Test getblockheader")
diff --git a/test/functional/rpc_getblockstats.py b/test/functional/rpc_getblockstats.py
index ebcf4e2ebb..19295b70e5 100755
--- a/test/functional/rpc_getblockstats.py
+++ b/test/functional/rpc_getblockstats.py
@@ -143,17 +143,17 @@ class GetblockstatsTest(BitcoinTestFramework):
         inv_sel_stat = 'asdfghjkl'
         inv_stats = [
             [inv_sel_stat],
-            ['minfee' , inv_sel_stat],
+            ['minfee', inv_sel_stat],
             [inv_sel_stat, 'minfee'],
             ['minfee', inv_sel_stat, 'maxfee'],
         ]
         for inv_stat in inv_stats:
-            assert_raises_rpc_error(-8, 'Invalid selected statistic %s' % inv_sel_stat,
+            assert_raises_rpc_error(-8, f"Invalid selected statistic '{inv_sel_stat}'",
                                     self.nodes[0].getblockstats, hash_or_height=1, stats=inv_stat)
 
         # Make sure we aren't always returning inv_sel_stat as the culprit stat
-        assert_raises_rpc_error(-8, 'Invalid selected statistic aaa%s' % inv_sel_stat,
-                                self.nodes[0].getblockstats, hash_or_height=1, stats=['minfee' , 'aaa%s' % inv_sel_stat])
+        assert_raises_rpc_error(-8, f"Invalid selected statistic 'aaa{inv_sel_stat}'",
+                                self.nodes[0].getblockstats, hash_or_height=1, stats=['minfee', f'aaa{inv_sel_stat}'])
         # Mainchain's genesis block shouldn't be found on regtest
         assert_raises_rpc_error(-5, 'Block not found', self.nodes[0].getblockstats,
                                 hash_or_height='000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f')