diff --git a/src/operators/geo_lookup.cc b/src/operators/geo_lookup.cc
index 5717b7af..6bd79185 100644
--- a/src/operators/geo_lookup.cc
+++ b/src/operators/geo_lookup.cc
@@ -30,8 +30,13 @@
 #include "src/utils/geo_lookup.h"
 
 
-namespace modsecurity {
-namespace operators {
+namespace modsecurity::operators {
+
+
+static bool debug(const Transaction *transaction, int x, const std::string &a) {
+    ms_dbg_a(transaction, x, a);
+    return true;
+}
 
 
 bool GeoLookup::evaluate(Transaction *trans, const std::string &exp) {
@@ -41,9 +46,9 @@ bool GeoLookup::evaluate(Transaction *trans, const std::string &exp) {
 
     if (trans) {
         ret = Utils::GeoLookup::getInstance().lookup(exp, trans,
-            std::bind(&GeoLookup::debug, this, trans, _1, _2));
+            std::bind(debug, trans, _1, _2));
     } else {
-        ret = Utils::GeoLookup::getInstance().lookup(exp, NULL,
+        ret = Utils::GeoLookup::getInstance().lookup(exp, nullptr,
             nullptr);
     }
 
@@ -51,5 +56,4 @@ bool GeoLookup::evaluate(Transaction *trans, const std::string &exp) {
 }
 
 
-}  // namespace operators
-}  // namespace modsecurity
+}  // namespace modsecurity::operators
diff --git a/src/operators/geo_lookup.h b/src/operators/geo_lookup.h
index 81155d61..b12b031a 100644
--- a/src/operators/geo_lookup.h
+++ b/src/operators/geo_lookup.h
@@ -21,8 +21,8 @@
 #include "src/operators/operator.h"
 
 
-namespace modsecurity {
-namespace operators {
+namespace modsecurity::operators {
+
 
 class GeoLookup : public Operator {
  public:
@@ -30,17 +30,10 @@ class GeoLookup : public Operator {
     GeoLookup()
         : Operator("GeoLookup") { }
     bool evaluate(Transaction *transaction, const std::string &exp) override;
-
- protected:
-    // cppcheck-suppress functionStatic
-    bool debug(const Transaction *transaction, int x, const std::string &a) {
-        ms_dbg_a(transaction, x, a);
-        return true;
-    }
 };
 
-}  // namespace operators
-}  // namespace modsecurity
+
+}  // namespace modsecurity::operators
 
 
 #endif  // SRC_OPERATORS_GEO_LOOKUP_H_