diff --git a/silkworm/rpc/http/json_rpc_validator.cpp b/silkworm/rpc/http/json_rpc_validator.cpp
index 11b0e63f7a..2f37576558 100644
--- a/silkworm/rpc/http/json_rpc_validator.cpp
+++ b/silkworm/rpc/http/json_rpc_validator.cpp
@@ -102,17 +102,17 @@ void JsonRpcValidator::check_request_fields(const nlohmann::json& request, JsonR
 }
 
 void JsonRpcValidator::validate_params(const nlohmann::json& request, JsonRpcValidationResult& result) {
-    const auto method = request.find(kRequestFieldMethod).value().get<std::string>();
-    const auto params_field = request.find(kRequestFieldParameters);
-    const auto params = params_field != request.end() ? params_field.value() : nlohmann::json::array();
+    const auto& method = request.find(kRequestFieldMethod).value().get<std::string>();
+    const auto& params_field = request.find(kRequestFieldParameters);
+    const auto& params = params_field != request.end() ? params_field.value() : nlohmann::json::array();
 
-    const auto method_spec_field = method_specs_.find(method);
+    const auto& method_spec_field = method_specs_.find(method);
     if (method_spec_field == method_specs_.end()) {
         result.is_valid = accept_unknown_methods_;
         result.error_message = "Method not found in spec";
         return;
     }
-    const auto method_spec = method_spec_field->second;
+    const auto& method_spec = method_spec_field->second;
 
     if (params.size() > method_spec.size()) {
         result.is_valid = false;
@@ -122,7 +122,7 @@ void JsonRpcValidator::validate_params(const nlohmann::json& request, JsonRpcVal
 
     unsigned long idx = 0;
     for (const auto& spec : method_spec) {
-        const auto spec_name = spec["name"].get<std::string>();
+        const auto& spec_name = spec["name"].get<std::string>();
         const auto& spec_schema = spec["schema"];
 
         if (params.size() <= idx) {
@@ -169,7 +169,7 @@ void JsonRpcValidator::validate_schema(const nlohmann::json& value, const nlohma
 }
 
 void JsonRpcValidator::validate_type(const nlohmann::json& value, const nlohmann::json& schema, JsonRpcValidationResult& result) {
-    const auto schema_type = schema["type"].get<std::string>();
+    const auto& schema_type = schema["type"].get<std::string>();
 
     if (schema_type == "string") {
         validate_string(value, schema, result);
@@ -196,16 +196,19 @@ void JsonRpcValidator::validate_string(const nlohmann::json& string, const nlohm
         return;
     }
 
-    const auto schema_pattern_field = schema.find("pattern");
+    const auto& schema_pattern_field = schema.find("pattern");
     if (schema_pattern_field != schema.end()) {
         boost::regex pattern;
-        const auto schema_pattern = schema_pattern_field.value().get<std::string>();
-        if (patterns_.find(schema_pattern) != patterns_.end()) {
-            pattern = patterns_[schema_pattern];
+        const auto& schema_pattern = schema_pattern_field.value().get<std::string>();
+
+        const auto& pattern_field = patterns_.find(schema_pattern);
+        if (pattern_field != patterns_.end()) {
+            pattern = pattern_field->second;
         } else {
             pattern = boost::regex(schema_pattern, boost::regex::optimize);
             patterns_[schema_pattern] = pattern;
         }
+
         if (!boost::regex_match(string.get<std::string>(), pattern)) {
             result.is_valid = false;
             result.error_message = "Invalid string pattern";
@@ -213,9 +216,10 @@ void JsonRpcValidator::validate_string(const nlohmann::json& string, const nlohm
         }
     }
 
-    if (schema.find("enum") != schema.end()) {
+    const auto& enum_field = schema.find("enum");
+    if (enum_field != schema.end()) {
         bool is_valid = false;
-        for (const auto& enum_value : schema["enum"]) {
+        for (const auto& enum_value : enum_field.value()) {
             if (string == enum_value) {
                 is_valid = true;
                 break;
diff --git a/silkworm/rpc/http/json_rpc_validator_test.cpp b/silkworm/rpc/http/json_rpc_validator_test.cpp
index 26316439af..7cb8b0145f 100644
--- a/silkworm/rpc/http/json_rpc_validator_test.cpp
+++ b/silkworm/rpc/http/json_rpc_validator_test.cpp
@@ -72,6 +72,51 @@ TEST_CASE("rpc::http::JsonRpcValidator detects missing request field", "[rpc][ht
     CHECK(result.error_message == "Request not valid, required fields: jsonrpc,id,method,params");
 }
 
+TEST_CASE("rpc::http::JsonRpcValidator validates invalid request fields", "[rpc][http][json_rpc_validator]") {
+    JsonRpcValidator validator{};
+
+    nlohmann::json request = {
+        {"jsonrpc", 2},
+        {"method", "eth_getBlockByNumber"},
+        {"params", {"0x0", true}},
+        {"id", 1},
+    };
+
+    JsonRpcValidationResult result = validator.validate(request);
+    CHECK(!result.is_valid);
+    CHECK(result.error_message == "Invalid field: jsonrpc");
+
+    request = {
+        {"jsonrpc", "2.0"},
+        {"method", 1},
+        {"params", {"0x0", true}},
+        {"id", 1},
+    };
+    result = validator.validate(request);
+    CHECK(!result.is_valid);
+    CHECK(result.error_message == "Invalid field: method");
+
+    request = {
+        {"jsonrpc", "2.0"},
+        {"method", "eth_getBlockByNumber"},
+        {"params", "params"},
+        {"id", 1},
+    };
+    result = validator.validate(request);
+    CHECK(!result.is_valid);
+    CHECK(result.error_message == "Invalid field: params");
+
+    request = {
+        {"jsonrpc", "2.0"},
+        {"method", "eth_getBlockByNumber"},
+        {"params", {"0x0", true}},
+        {"id", "1"},
+    };
+    result = validator.validate(request);
+    CHECK(!result.is_valid);
+    CHECK(result.error_message == "Invalid field: id");
+}
+
 TEST_CASE("rpc::http::JsonRpcValidator accepts missing params field", "[rpc][http][json_rpc_validator]") {
     JsonRpcValidator validator{};