diff --git a/include/extractor/guidance/classification_data.hpp b/include/extractor/guidance/classification_data.hpp
index 754c4f2d4..53f54cf46 100644
--- a/include/extractor/guidance/classification_data.hpp
+++ b/include/extractor/guidance/classification_data.hpp
@@ -1,12 +1,9 @@
 #ifndef OSRM_EXTRACTOR_CLASSIFICATION_DATA_HPP_
 #define OSRM_EXTRACTOR_CLASSIFICATION_DATA_HPP_
 
-#include "util/simple_logger.hpp"
-
 #include <cstdint>
 
 #include <string>
-#include <unordered_map>
 
 // Forward Declaration to allow usage of external osmium::Way
 namespace osmium
@@ -41,43 +38,7 @@ enum class FunctionalRoadClass : std::uint8_t
     LOW_PRIORITY_ROAD // a road simply included for connectivity. Should be avoided at all cost
 };
 
-inline FunctionalRoadClass functionalRoadClassFromTag(std::string const &value)
-{
-    // FIXME at some point this should be part of the profiles
-    const static auto class_hash = []
-    {
-        std::unordered_map<std::string, FunctionalRoadClass> hash;
-        hash["motorway"] = FunctionalRoadClass::MOTORWAY;
-        hash["motorway_link"] = FunctionalRoadClass::MOTORWAY_LINK;
-        hash["trunk"] = FunctionalRoadClass::TRUNK;
-        hash["trunk_link"] = FunctionalRoadClass::TRUNK_LINK;
-        hash["primary"] = FunctionalRoadClass::PRIMARY;
-        hash["primary_link"] = FunctionalRoadClass::PRIMARY_LINK;
-        hash["secondary"] = FunctionalRoadClass::SECONDARY;
-        hash["secondary_link"] = FunctionalRoadClass::SECONDARY_LINK;
-        hash["tertiary"] = FunctionalRoadClass::TERTIARY;
-        hash["tertiary_link"] = FunctionalRoadClass::TERTIARY_LINK;
-        hash["unclassified"] = FunctionalRoadClass::UNCLASSIFIED;
-        hash["residential"] = FunctionalRoadClass::RESIDENTIAL;
-        hash["service"] = FunctionalRoadClass::SERVICE;
-        hash["living_street"] = FunctionalRoadClass::LIVING_STREET;
-        hash["track"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
-        hash["road"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
-        hash["path"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
-        hash["driveway"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
-        return hash;
-    }();
-
-    if (class_hash.find(value) != class_hash.end())
-    {
-        return class_hash.find(value)->second;
-    }
-    else
-    {
-        util::SimpleLogger().Write(logDEBUG) << "Unknown road class encountered: " << value;
-        return FunctionalRoadClass::UNKNOWN;
-    }
-}
+FunctionalRoadClass functionalRoadClassFromTag(std::string const &tag);
 
 inline bool isRampClass(const FunctionalRoadClass road_class)
 {
diff --git a/src/extractor/guidance/classification_data.cpp b/src/extractor/guidance/classification_data.cpp
new file mode 100644
index 000000000..70ccaff1c
--- /dev/null
+++ b/src/extractor/guidance/classification_data.cpp
@@ -0,0 +1,53 @@
+#include "extractor/guidance/classification_data.hpp"
+#include "util/simple_logger.hpp"
+
+#include <unordered_map>
+
+namespace osrm
+{
+namespace extractor
+{
+namespace guidance
+{
+
+FunctionalRoadClass functionalRoadClassFromTag(std::string const &value)
+{
+    // FIXME at some point this should be part of the profiles
+    const static auto class_hash = []
+    {
+        std::unordered_map<std::string, FunctionalRoadClass> hash;
+        hash["motorway"] = FunctionalRoadClass::MOTORWAY;
+        hash["motorway_link"] = FunctionalRoadClass::MOTORWAY_LINK;
+        hash["trunk"] = FunctionalRoadClass::TRUNK;
+        hash["trunk_link"] = FunctionalRoadClass::TRUNK_LINK;
+        hash["primary"] = FunctionalRoadClass::PRIMARY;
+        hash["primary_link"] = FunctionalRoadClass::PRIMARY_LINK;
+        hash["secondary"] = FunctionalRoadClass::SECONDARY;
+        hash["secondary_link"] = FunctionalRoadClass::SECONDARY_LINK;
+        hash["tertiary"] = FunctionalRoadClass::TERTIARY;
+        hash["tertiary_link"] = FunctionalRoadClass::TERTIARY_LINK;
+        hash["unclassified"] = FunctionalRoadClass::UNCLASSIFIED;
+        hash["residential"] = FunctionalRoadClass::RESIDENTIAL;
+        hash["service"] = FunctionalRoadClass::SERVICE;
+        hash["living_street"] = FunctionalRoadClass::LIVING_STREET;
+        hash["track"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
+        hash["road"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
+        hash["path"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
+        hash["driveway"] = FunctionalRoadClass::LOW_PRIORITY_ROAD;
+        return hash;
+    }();
+
+    if (class_hash.find(value) != class_hash.end())
+    {
+        return class_hash.find(value)->second;
+    }
+    else
+    {
+        util::SimpleLogger().Write(logDEBUG) << "Unknown road class encountered: " << value;
+        return FunctionalRoadClass::UNKNOWN;
+    }
+}
+
+} // ns guidance
+} // ns extractor
+} // ns osrm