diff --git a/Server/DataStructures/BaseDataFacade.h b/Server/DataStructures/BaseDataFacade.h
index 23d2aaf2e..8abd7b0a9 100644
--- a/Server/DataStructures/BaseDataFacade.h
+++ b/Server/DataStructures/BaseDataFacade.h
@@ -36,7 +36,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../../data_structures/turn_instructions.hpp"
 #include "../../Util/integer_range.hpp"
 #include "../../Util/OSRMException.h"
-#include "../../Util/StringUtil.h"
+#include "../../Util/string_util.hpp"
 #include "../../typedefs.h"
 
 #include <osrm/Coordinate.h>
diff --git a/Server/RequestHandler.cpp b/Server/RequestHandler.cpp
index f8ad568f1..b1178ba2b 100644
--- a/Server/RequestHandler.cpp
+++ b/Server/RequestHandler.cpp
@@ -34,7 +34,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../Library/OSRM.h"
 #include "../Util/json_renderer.hpp"
 #include "../Util/simple_logger.hpp"
-#include "../Util/StringUtil.h"
+#include "../Util/string_util.hpp"
 #include "../typedefs.h"
 
 #include <osrm/Reply.h>
diff --git a/Util/StringUtil.h b/Util/string_util.hpp
similarity index 97%
rename from Util/StringUtil.h
rename to Util/string_util.hpp
index e6d8e043c..5803a3c02 100644
--- a/Util/StringUtil.h
+++ b/Util/string_util.hpp
@@ -25,8 +25,8 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 */
 
-#ifndef STRINGUTIL_H
-#define STRINGUTIL_H
+#ifndef STRING_UTIL_HPP
+#define STRING_UTIL_HPP
 
 #include <boost/algorithm/string.hpp>
 
@@ -154,7 +154,7 @@ inline std::string GetRandomString()
                                    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                                    "abcdefghijklmnopqrstuvwxyz";
 
-    for (int i = 0; i < 127; ++i)
+    for (std::size_t i = 0; i < 127; ++i)
     {
         s[i] = alphanum[rand() % (sizeof(alphanum) - 1)];
     }
@@ -162,4 +162,4 @@ inline std::string GetRandomString()
     return s;
 }
 
-#endif // STRINGUTIL_H
+#endif // STRING_UTIL_HPP
diff --git a/algorithms/object_encoder.hpp b/algorithms/object_encoder.hpp
index 64c03c1be..af6e0d9ca 100644
--- a/algorithms/object_encoder.hpp
+++ b/algorithms/object_encoder.hpp
@@ -28,7 +28,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef OBJECT_ENCODER_HPP
 #define OBJECT_ENCODER_HPP
 
-#include "../Util/StringUtil.h"
+#include "../Util/string_util.hpp"
 
 #include <boost/assert.hpp>
 #include <boost/archive/iterators/base64_from_binary.hpp>
diff --git a/contractor/contractor.hpp b/contractor/contractor.hpp
index ecfefbc7a..c8c107cdb 100644
--- a/contractor/contractor.hpp
+++ b/contractor/contractor.hpp
@@ -37,7 +37,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../data_structures/xor_fast_hash_storage.hpp"
 #include "../Util/integer_range.hpp"
 #include "../Util/simple_logger.hpp"
-#include "../Util/StringUtil.h"
 #include "../Util/timing_util.hpp"
 #include "../typedefs.h"
 
diff --git a/contractor/processing_chain.cpp b/contractor/processing_chain.cpp
index 0b5ce05e6..c5872a878 100644
--- a/contractor/processing_chain.cpp
+++ b/contractor/processing_chain.cpp
@@ -41,7 +41,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../Util/make_unique.hpp"
 #include "../Util/OSRMException.h"
 #include "../Util/simple_logger.hpp"
-#include "../Util/StringUtil.h"
+#include "../Util/string_util.hpp"
 #include "../Util/timing_util.hpp"
 #include "../typedefs.h"
 
diff --git a/data_structures/Coordinate.cpp b/data_structures/Coordinate.cpp
index bc1cae1f8..4305256ef 100644
--- a/data_structures/Coordinate.cpp
+++ b/data_structures/Coordinate.cpp
@@ -30,7 +30,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #ifndef NDEBUG
 #include "../Util/simple_logger.hpp"
 #endif
-#include "../Util/StringUtil.h"
+#include "../Util/string_util.hpp"
 
 #include <boost/assert.hpp>
 
diff --git a/descriptors/json_descriptor.hpp b/descriptors/json_descriptor.hpp
index 1e9094309..94efcd14c 100644
--- a/descriptors/json_descriptor.hpp
+++ b/descriptors/json_descriptor.hpp
@@ -39,7 +39,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../Util/integer_range.hpp"
 #include "../Util/json_renderer.hpp"
 #include "../Util/simple_logger.hpp"
-#include "../Util/StringUtil.h"
+#include "../Util/string_util.hpp"
 #include "../Util/timing_util.hpp"
 
 #include <algorithm>
diff --git a/plugins/distance_table.hpp b/plugins/distance_table.hpp
index 09657b47d..e28dada82 100644
--- a/plugins/distance_table.hpp
+++ b/plugins/distance_table.hpp
@@ -37,7 +37,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../descriptors/descriptor_base.hpp"
 #include "../Util/json_renderer.hpp"
 #include "../Util/make_unique.hpp"
-#include "../Util/StringUtil.h"
+#include "../Util/string_util.hpp"
 #include "../Util/timing_util.hpp"
 
 #include <cstdlib>
diff --git a/plugins/locate.hpp b/plugins/locate.hpp
index f53ab1bf4..6171395c4 100644
--- a/plugins/locate.hpp
+++ b/plugins/locate.hpp
@@ -32,7 +32,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "../data_structures/json_container.hpp"
 #include "../Util/json_renderer.hpp"
-#include "../Util/StringUtil.h"
+#include "../Util/string_util.hpp"
 
 #include <string>