diff --git a/headers/modsecurity/rule.h b/headers/modsecurity/rule.h
index 0660c626..f9552e73 100644
--- a/headers/modsecurity/rule.h
+++ b/headers/modsecurity/rule.h
@@ -56,7 +56,7 @@ class Rule {
             std::vector<actions::Action *> *_actions,
             std::string fileName,
             int lineNumber);
-    explicit Rule(std::string marker);
+    explicit Rule(const std::string &marker);
     virtual ~Rule();
 
     virtual bool evaluate(Transaction *transaction,
@@ -87,7 +87,7 @@ class Rule {
         std::shared_ptr<std::string>>> executeDefaultTransformations(
         Transaction *trasn, const std::string &value);
 
-    bool executeOperatorAt(Transaction *trasn, std::string key,
+    bool executeOperatorAt(Transaction *trasn, const std::string &key,
         std::string value, std::shared_ptr<RuleMessage> rm);
     void executeActionsIndependentOfChainedRuleResult(Transaction *trasn,
         bool *b, std::shared_ptr<RuleMessage> ruleMessage);
diff --git a/headers/modsecurity/transaction.h b/headers/modsecurity/transaction.h
index dd2e9cf8..b6161aba 100644
--- a/headers/modsecurity/transaction.h
+++ b/headers/modsecurity/transaction.h
@@ -293,6 +293,10 @@ class Transaction : public TransactionAnchoredVariables {
         void *logCbData);
     ~Transaction();
 
+    Transaction ( const Transaction & ) = delete;
+    bool operator ==(const Transaction &b) const { return false; };
+    Transaction operator =(const Transaction &b) const = delete;
+
     /** TODO: Should be an structure that fits an IP address */
     int processConnection(const char *client, int cPort,
         const char *server, int sPort);
diff --git a/src/operators/contains_word.cc b/src/operators/contains_word.cc
index 5b548739..3254e273 100644
--- a/src/operators/contains_word.cc
+++ b/src/operators/contains_word.cc
@@ -37,36 +37,36 @@ bool ContainsWord::acceptableChar(const std::string& a, size_t pos) {
 }
 
 bool ContainsWord::evaluate(Transaction *transaction, Rule *rule,
-    const std::string &input, std::shared_ptr<RuleMessage> ruleMessage) {
+    const std::string &str, std::shared_ptr<RuleMessage> ruleMessage) {
     std::string paramTarget(m_string->evaluate(transaction));
 
     if (paramTarget.empty()) {
         return true;
     }
-    if (input.empty()) {
+    if (str.empty()) {
         return false;
     }
-    if (input == paramTarget) {
+    if (str == paramTarget) {
         return true;
     }
 
-    size_t pos = input.find(paramTarget);
+    size_t pos = str.find(paramTarget);
     while (pos != std::string::npos) {
-        if (pos == 0 && acceptableChar(input, paramTarget.size())) {
+        if (pos == 0 && acceptableChar(str, paramTarget.size())) {
             logOffset(ruleMessage, 0, paramTarget.size());
             return true;
         }
-        if (pos + paramTarget.size() == input.size() &&
-            acceptableChar(input, pos - 1)) {
+        if (pos + paramTarget.size() == str.size() &&
+            acceptableChar(str, pos - 1)) {
             logOffset(ruleMessage, pos, paramTarget.size());
             return true;
         }
-        if (acceptableChar(input, pos - 1) &&
-            acceptableChar(input, pos + paramTarget.size())) {
+        if (acceptableChar(str, pos - 1) &&
+            acceptableChar(str, pos + paramTarget.size())) {
             logOffset(ruleMessage, pos, paramTarget.size());
             return true;
         }
-        pos = input.find(paramTarget, pos + 1);
+        pos = str.find(paramTarget, pos + 1);
     }
 
     return false;
diff --git a/src/operators/ends_with.cc b/src/operators/ends_with.cc
index f1f20247..d967ecf5 100644
--- a/src/operators/ends_with.cc
+++ b/src/operators/ends_with.cc
@@ -24,15 +24,15 @@ namespace operators {
 
 
 bool EndsWith::evaluate(Transaction *transaction, Rule *rule,
-    const std::string &input, std::shared_ptr<RuleMessage> ruleMessage) {
+    const std::string &str, std::shared_ptr<RuleMessage> ruleMessage) {
     bool ret = false;
     std::string p(m_string->evaluate(transaction));
 
-    if (input.length() >= p.length()) {
-        ret = (0 == input.compare(input.length() - p.length(),
+    if (str.length() >= p.length()) {
+        ret = (0 == str.compare(str.length() - p.length(),
             p.length(), p));
         if (ret) {
-            logOffset(ruleMessage, input.length() - p.length(),
+            logOffset(ruleMessage, str.length() - p.length(),
                       p.size());
         }
     }
diff --git a/src/operators/fuzzy_hash.h b/src/operators/fuzzy_hash.h
index cafe5780..2a1e7df8 100644
--- a/src/operators/fuzzy_hash.h
+++ b/src/operators/fuzzy_hash.h
@@ -40,8 +40,8 @@ class FuzzyHash : public Operator {
     /** @ingroup ModSecurity_Operator */
     explicit FuzzyHash(std::unique_ptr<RunTimeString> param)
         : Operator("FuzzyHash", std::move(param)),
-        m_head(NULL),
-        m_threshold(0) { }
+        m_threshold(0),
+        m_head(NULL) { }
     ~FuzzyHash();
 
     bool evaluate(Transaction *transaction, const std::string &std) override;
diff --git a/src/operators/rbl.cc b/src/operators/rbl.cc
index 5cf794d9..dc7e0f6e 100644
--- a/src/operators/rbl.cc
+++ b/src/operators/rbl.cc
@@ -34,7 +34,7 @@ std::string Rbl::mapIpToAddress(std::string ipStr, Transaction *trans) {
     std::string addr;
     int h0, h1, h2, h3;
     std::string key;
-    if (trans->m_rules->m_httpblKey.m_set == true) {
+    if (trans && trans->m_rules->m_httpblKey.m_set == true) {
         key = trans->m_rules->m_httpblKey.m_value;
     }
 
diff --git a/src/rule.cc b/src/rule.cc
index 071526e6..561ef537 100644
--- a/src/rule.cc
+++ b/src/rule.cc
@@ -51,7 +51,7 @@ using variables::Variable;
 using actions::transformations::None;
 
 
-Rule::Rule(std::string marker)
+Rule::Rule(const std::string &marker)
     : m_accuracy(0),
     m_actionsRuntimePos(),
     m_actionsRuntimePre(),
@@ -303,7 +303,7 @@ void Rule::executeActionsIndependentOfChainedRuleResult(Transaction *trans,
 }
 
 
-bool Rule::executeOperatorAt(Transaction *trans, std::string key,
+bool Rule::executeOperatorAt(Transaction *trans, const std::string &key,
     std::string value, std::shared_ptr<RuleMessage> ruleMessage) {
 #if MSC_EXEC_CLOCK_ENABLED
     clock_t begin = clock();
diff --git a/src/utils/base64.h b/src/utils/base64.h
index ab63449e..8d3d91c0 100644
--- a/src/utils/base64.h
+++ b/src/utils/base64.h
@@ -32,9 +32,10 @@ class Base64 {
     static std::string decode(const std::string& data);
     static std::string decode_forgiven(const std::string& data);
 
-    static void decode_forgiven_engine(unsigned char *output,
-        size_t output_size, size_t *aiming_size, const unsigned char *input,
-        size_t input_size);
+    static void decode_forgiven_engine(unsigned char *plain_text,
+        size_t plain_text_size, size_t *aiming_size,
+        const unsigned char *encoded,
+        size_t input_len);
 };
 
 
diff --git a/src/utils/geo_lookup.cc b/src/utils/geo_lookup.cc
index 2e95244b..2be7e8f9 100644
--- a/src/utils/geo_lookup.cc
+++ b/src/utils/geo_lookup.cc
@@ -106,7 +106,7 @@ bool GeoLookup::setDataBase(const std::string& filePath,
 
 
 bool GeoLookup::lookup(const std::string& target, Transaction *trans,
-    std::function<bool(int, std::string)> debug) {
+    std::function<bool(int, std::string)> debug) const {
 
     if (m_version == NOT_LOADED) {
         if (debug) {
diff --git a/src/utils/geo_lookup.h b/src/utils/geo_lookup.h
index c1e3ab49..28384605 100644
--- a/src/utils/geo_lookup.h
+++ b/src/utils/geo_lookup.h
@@ -49,8 +49,8 @@ class GeoLookup {
     bool setDataBase(const std::string& filePath, std::string *err);
     void cleanUp();
 
-    bool lookup(const std::string& target, Transaction *t,
-        std::function<bool(int, std::string)> callback);
+    bool lookup(const std::string& target, Transaction *transaction,
+        std::function<bool(int, std::string)> debug) const;
 
  private:
     GeoLookup() :
diff --git a/src/utils/https_client.cc b/src/utils/https_client.cc
index 5db88a2c..6192de77 100644
--- a/src/utils/https_client.cc
+++ b/src/utils/https_client.cc
@@ -50,8 +50,8 @@ void HttpsClient::setKey(const std::string& key) {
     m_key = "ModSec-key: " + key;
 }
 
-void HttpsClient::setRequestBody(const std::string& requestBody) {
-    m_requestBody = requestBody;
+void HttpsClient::setRequestBody(const std::string& requestType) {
+    m_requestBody = requestType;
 }
 
 void HttpsClient::setRequestType(const std::string& requestType) {
diff --git a/src/utils/regex.h b/src/utils/regex.h
index 92eb118b..2a52bfb1 100644
--- a/src/utils/regex.h
+++ b/src/utils/regex.h
@@ -58,7 +58,7 @@ class Regex {
     Regex& operator=(const Regex&) = delete;
 
     std::list<SMatch> searchAll(const std::string& s) const;
-    int search(const std::string &s, SMatch *m) const;
+    int search(const std::string &s, SMatch *match) const;
     int search(const std::string &s) const;
 
     const std::string pattern;
diff --git a/src/utils/system.h b/src/utils/system.h
index 04ef35a9..c80a6ced 100644
--- a/src/utils/system.h
+++ b/src/utils/system.h
@@ -29,7 +29,7 @@ namespace utils {
 
 
 double cpu_seconds(void);
-std::string find_resource(const std::string& file, const std::string& param,
+std::string find_resource(const std::string& file, const std::string& config,
     std::string *err);
 std::string get_path(const std::string& file);
 std::list<std::string> expandEnv(const std::string& var, int flags);
diff --git a/src/variables/variable.cc b/src/variables/variable.cc
index 84b9d632..4565ef1d 100644
--- a/src/variables/variable.cc
+++ b/src/variables/variable.cc
@@ -28,7 +28,7 @@ namespace modsecurity {
 namespace variables {
 
 
-Variable::Variable(std::string name)
+Variable::Variable(const std::string &name)
     : m_name(name),
     m_collectionName("") {
     size_t a = m_name.find(":");
diff --git a/src/variables/variable.h b/src/variables/variable.h
index 7f00a698..4f6c627c 100644
--- a/src/variables/variable.h
+++ b/src/variables/variable.h
@@ -539,7 +539,7 @@ class VariableMonkeyResolution {
 
 class Variable : public VariableMonkeyResolution {
  public:
-    explicit Variable(std::string _name);
+    explicit Variable(const std::string &name);
     explicit Variable(Variable *_name);
     virtual ~Variable() { }
 
diff --git a/src/variables/xml.h b/src/variables/xml.h
index 1ffae96f..eba59561 100644
--- a/src/variables/xml.h
+++ b/src/variables/xml.h
@@ -42,7 +42,7 @@ class XML_NoDictElement : public Variable {
         m_var(&m_name, &m_plain) {
         }
 
-    void evaluate(Transaction *transaction,
+    void evaluate(Transaction *t,
         Rule *rule,
         std::vector<const VariableValue *> *l) override {
         l->push_back(new VariableValue(&m_var));
diff --git a/test/cppcheck_suppressions.txt b/test/cppcheck_suppressions.txt
index 114543d4..16c9269e 100644
--- a/test/cppcheck_suppressions.txt
+++ b/test/cppcheck_suppressions.txt
@@ -57,3 +57,14 @@ useStlAlgorithm:test/regression/regression.cc:493
 useStlAlgorithm:test/unit/unit.cc:174
 useStlAlgorithm:test/unit/unit.cc:209
 variableScope:src/operators/verify_cpf.cc:45
+unusedFunction
+funcArgNamesDifferent
+preprocessorErrorDirective
+useStlAlgorithm
+functionStatic:test/regression/regression_test.h:36
+missingInclude
+toomanyconfigs
+functionStatic:src/unique_id.h:49
+functionStatic:src/unique_id.h:50
+functionConst:src/utils/geo_lookup.h:49
+functionStatic:headers/modsecurity/transaction.h:374
\ No newline at end of file
diff --git a/test/regression/custom_debug_log.cc b/test/regression/custom_debug_log.cc
index bffcfa7d..093d8175 100644
--- a/test/regression/custom_debug_log.cc
+++ b/test/regression/custom_debug_log.cc
@@ -36,13 +36,13 @@ void CustomDebugLog::write(int level, const std::string &id,
     m_log << msgf << std::endl;
 }
 
-bool CustomDebugLog::contains(const std::string& pattern) {
+bool const CustomDebugLog::contains(const std::string& pattern) const {
     modsecurity::Utils::Regex re(pattern);
     std::string s = m_log.str();
     return modsecurity::Utils::regex_search(s, re);
 }
 
-std::string CustomDebugLog::log_messages() {
+std::string const CustomDebugLog::log_messages() const {
     return m_log.str();
 }
 
diff --git a/test/regression/custom_debug_log.h b/test/regression/custom_debug_log.h
index 5ec1849c..a4cfaf83 100644
--- a/test/regression/custom_debug_log.h
+++ b/test/regression/custom_debug_log.h
@@ -31,8 +31,8 @@ class CustomDebugLog : public modsecurity::debug_log::DebugLog {
     void write(int level, const std::string& message) override;
     void write(int level, const std::string &id,
         const std::string &uri, const std::string &msg) override;
-    bool contains(const std::string& pattern);
-    std::string log_messages();
+    bool const contains(const std::string& pattern) const;
+    std::string const log_messages() const;
     std::string error_log_messages();
     int getDebugLogLevel() override;
 
diff --git a/test/regression/regression_test.cc b/test/regression/regression_test.cc
index 881ba872..453b1ca9 100644
--- a/test/regression/regression_test.cc
+++ b/test/regression/regression_test.cc
@@ -23,7 +23,7 @@
 
 namespace modsecurity_test {
 
-std::string RegressionTest::print() {
+const std::string RegressionTest::print() {
     std::stringstream i;
 
 #if 0
diff --git a/test/regression/regression_test.h b/test/regression/regression_test.h
index 557271f9..bde672a2 100644
--- a/test/regression/regression_test.h
+++ b/test/regression/regression_test.h
@@ -33,7 +33,7 @@ class RegressionTest {
  public:
     static RegressionTest *from_yajl_node(const yajl_val &);
 
-    std::string print();
+    const std::string print();
     std::string filename;
     std::string name;
     std::string title;
diff --git a/test/unit/unit_test.cc b/test/unit/unit_test.cc
index 23bbcb23..bface739 100644
--- a/test/unit/unit_test.cc
+++ b/test/unit/unit_test.cc
@@ -119,7 +119,7 @@ std::string UnitTest::print() {
 }
 
 
-UnitTest *UnitTest::from_yajl_node(yajl_val &node) {
+UnitTest *UnitTest::from_yajl_node(const yajl_val &node) {
     size_t num_tests = node->u.object.len;
     UnitTest *u = new UnitTest();
 
diff --git a/test/unit/unit_test.h b/test/unit/unit_test.h
index 34aa5914..213c1b5c 100644
--- a/test/unit/unit_test.h
+++ b/test/unit/unit_test.h
@@ -27,7 +27,7 @@ namespace modsecurity_test {
 
 class UnitTest {
  public:
-    static UnitTest *from_yajl_node(yajl_val &);
+    static UnitTest *from_yajl_node(const yajl_val &);
 
     std::string print();