diff --git a/arangod/Agency/Supervision.cpp b/arangod/Agency/Supervision.cpp
index f866f4403c..6f10af52d4 100644
--- a/arangod/Agency/Supervision.cpp
+++ b/arangod/Agency/Supervision.cpp
@@ -462,7 +462,7 @@ void Supervision::run() {
           }
         }
       }
-      _cv.wait(1000000 * _frequency);
+      _cv.wait(static_cast<uint64_t>(1000000 * _frequency));
     }
   }
   if (shutdown) {
diff --git a/arangod/Aql/EnumerateCollectionBlock.cpp b/arangod/Aql/EnumerateCollectionBlock.cpp
index fdf236b701..4e4948ba01 100644
--- a/arangod/Aql/EnumerateCollectionBlock.cpp
+++ b/arangod/Aql/EnumerateCollectionBlock.cpp
@@ -135,7 +135,7 @@ int EnumerateCollectionBlock::initialize() {
       inSync = std::find(followers.begin(), followers.end(), ServerState::instance()->getId()) != followers.end();
       if (!inSync) {
         if (endTime - now < waitInterval) {
-          waitInterval = endTime - now;
+          waitInterval = static_cast<unsigned long>(endTime - now);
         }
         usleep(waitInterval);
       }
diff --git a/arangod/V8Server/v8-vocbase.cpp b/arangod/V8Server/v8-vocbase.cpp
index 46edfa6b94..7613ae72f3 100644
--- a/arangod/V8Server/v8-vocbase.cpp
+++ b/arangod/V8Server/v8-vocbase.cpp
@@ -2733,7 +2733,7 @@ static void JS_DecodeRev(v8::FunctionCallbackInfo<v8::Value> const& args) {
 #endif
   char buffer[32];
   strftime(buffer, 32, "%Y-%m-%dT%H:%M:%S.000Z", &date);
-  buffer[20] = (millis / 100) + '0';
+  buffer[20] = static_cast<char>(millis / 100) + '0';
   buffer[21] = ((millis / 10) % 10) + '0';
   buffer[22] = (millis % 10) + '0';
   buffer[24] = 0;
@@ -2742,7 +2742,7 @@ static void JS_DecodeRev(v8::FunctionCallbackInfo<v8::Value> const& args) {
   result->Set(TRI_V8_ASCII_STRING("date"),
               TRI_V8_ASCII_STRING(buffer));
   result->Set(TRI_V8_ASCII_STRING("count"),
-              v8::Number::New(isolate, count));
+              v8::Number::New(isolate, static_cast<double>(count)));
 
   TRI_V8_RETURN(result);
   
diff --git a/lib/Basics/fasthash.cpp b/lib/Basics/fasthash.cpp
index ceaee8262a..c5ca3360ef 100644
--- a/lib/Basics/fasthash.cpp
+++ b/lib/Basics/fasthash.cpp
@@ -24,6 +24,8 @@
 */
 
 #include "fasthash.h"
+  
+static constexpr uint64_t m = 0x880355f21e6d1965ULL;
 
 // Compression function for Merkle-Damgard construction.
 // This function is generated using the framework provided.
@@ -37,9 +39,7 @@ static inline uint64_t mix(uint64_t h) {
 }
 
 uint64_t fasthash64_uint64(uint64_t value, uint64_t seed) {
-  size_t const len = sizeof(uint64_t);
-  uint64_t const m = 0x880355f21e6d1965ULL;
-  uint64_t h = seed ^ (len * m);
+  uint64_t h = seed ^ 4619197404915747624ULL; // this is h = seed ^ (sizeof(uint64_t) * m), but prevents VS warning C4307: integral constant overflow 
   h ^= mix(value);
   h *= m;
 
@@ -51,7 +51,6 @@ uint64_t fasthash64(const void* buf, size_t len, uint64_t seed) {
   // byte-wise hashing to support platforms that don't permit
   // unaligned accesses of uint64_t values (which is the default
   // memory access strategy of fasthash64)
-  uint64_t const m = 0x880355f21e6d1965ULL;
   uint8_t const* pos = (uint8_t const*)buf;
   uint8_t const* end = pos + len;
   uint64_t h = seed ^ (len * m);
@@ -92,7 +91,6 @@ uint64_t fasthash64(const void* buf, size_t len, uint64_t seed) {
   // uint64_t-wise hashing for platforms that allow dereferencing
   // unaligned pointers to uint64_t memory
   // this is the original version of fasthash64
-  uint64_t const m = 0x880355f21e6d1965ULL;
   uint64_t const* pos = (uint64_t const*)buf;
   uint64_t const* end = pos + (len / 8);
   const unsigned char* pos2;
@@ -104,7 +102,7 @@ uint64_t fasthash64(const void* buf, size_t len, uint64_t seed) {
     h ^= mix(v);
     h *= m;
   }
-
+  
   pos2 = (const unsigned char*)pos;
   v = 0;