diff --git a/include/hpp/statistics/success-bin.hh b/include/hpp/statistics/success-bin.hh
index 292e1248cf4d7a32a4a87e5d9a16959636d2573f..11c979e542a626480c0472d66ed4ecc9a6825e37 100644
--- a/include/hpp/statistics/success-bin.hh
+++ b/include/hpp/statistics/success-bin.hh
@@ -112,13 +112,13 @@ namespace hpp {
         void addFailure (const SuccessBin::Reason& r = SuccessBin::REASON_UNKNOWN);
 
         /// Count the number of success.
-        unsigned int nbSuccess () const;
+        std::size_t nbSuccess () const;
 
         /// Count the number of failure, in total.
-        unsigned int nbFailure () const;
+        std::size_t nbFailure () const;
 
         /// Count the number of a particular failure.
-        unsigned int nbFailure (const SuccessBin::Reason& r) const;
+        std::size_t nbFailure (const SuccessBin::Reason& r) const;
     };
   } // namespace statistics
 } // namespace hpp
diff --git a/src/success-bin.cc b/src/success-bin.cc
index dff220a8f7b08789e64287c5c2cb9b6bf8622297..69e9b3f50a36f1f919fd90aab24aace3f8bc7b43 100644
--- a/src/success-bin.cc
+++ b/src/success-bin.cc
@@ -77,17 +77,17 @@ namespace hpp {
       insert (SuccessBin (true));
     }
 
-    unsigned int SuccessStatistics::nbSuccess () const
+    std::size_t SuccessStatistics::nbSuccess() const
     {
       return freq (SuccessBin(true));
     }
 
-    unsigned int SuccessStatistics::nbFailure () const
+    std::size_t SuccessStatistics::nbFailure() const
     {
       return numberOfObservations() - nbSuccess();
     }
 
-    unsigned int SuccessStatistics::nbFailure (const SuccessBin::Reason& r) const
+    std::size_t SuccessStatistics::nbFailure(const SuccessBin::Reason& r) const
     {
       return freq (SuccessBin (false, r));
     }
diff --git a/tests/test-distribution.cc b/tests/test-distribution.cc
index 6bf22b0ccf17db0ba37bd04a7bf5fb8d86e6b3d5..276635ceb89acf09dd229a39528e551e64dc5686 100644
--- a/tests/test-distribution.cc
+++ b/tests/test-distribution.cc
@@ -109,7 +109,7 @@ int test2 ()
 
 int main () {
   /* initialize random seed: */
-  srand (time(NULL));
+  srand (static_cast<unsigned int> (time(NULL)));
 
   std::cout.precision(15);
 
diff --git a/tests/test-statistics.cc b/tests/test-statistics.cc
index 786f839c926cee8fd4988ab9a97eed3ab3a21600..56f03cd3d4a06fb19db7edf6786bbbc5e1b1a4a2 100644
--- a/tests/test-statistics.cc
+++ b/tests/test-statistics.cc
@@ -60,7 +60,7 @@ class TestStatistics : public Statistics <TestBin> {
 
 int main ()
 {
-  srand (time(NULL));
+  srand (static_cast<unsigned int> (time(NULL)));
 
   TestStatistics t;
   double *check = new double [100];
diff --git a/tests/test-successstatistics.cc b/tests/test-successstatistics.cc
index 1f3826d177700cdc70b4e635f0e3aab9255bb22e..bd4c7f5bc03626080f85cbf47d8b6f7321d65222 100644
--- a/tests/test-successstatistics.cc
+++ b/tests/test-successstatistics.cc
@@ -27,7 +27,7 @@ using namespace hpp;
 int main ()
 {
   /* initialize random seed: */
-  srand (time(NULL));
+    srand (static_cast<unsigned int> (time(NULL)));
 
   using namespace hpp::statistics;
   SuccessStatistics ss;