diff --git a/src/core/int64x64-double.h b/src/core/int64x64-double.h
index c83bc35d0..6a53cf68a 100644
--- a/src/core/int64x64-double.h
+++ b/src/core/int64x64-double.h
@@ -11,13 +11,19 @@ class int64x64_t
 public:
   inline int64x64_t ()
     : _v (0) {}
-  explicit inline int64x64_t (double v)
+  inline int64x64_t (double v)
     : _v (v) {}
-  explicit inline int64x64_t (int v)
+  inline int64x64_t (int v)
     : _v (v) {}
-  explicit inline int64x64_t (long int v)
+  inline int64x64_t (long int v)
     : _v (v) {}
-  explicit inline int64x64_t (long long int v)
+  inline int64x64_t (long long int v)
+    : _v (v) {}
+  inline int64x64_t (unsigned int v)
+    : _v (v) {}
+  inline int64x64_t (unsigned long int v)
+    : _v (v) {}
+  inline int64x64_t (unsigned long long int v)
     : _v (v) {}
   inline int64x64_t (int64_t hi, uint64_t lo)
     : _v (hi) {/* XXX */}
diff --git a/src/core/int64x64.h b/src/core/int64x64.h
index 797160017..0d5425f33 100644
--- a/src/core/int64x64.h
+++ b/src/core/int64x64.h
@@ -3,7 +3,7 @@
 
 #include "ns3/core-config.h"
 
-#if defined (INT64X64_USE_DOUBLE)
+#if defined (INT64X64_USE_DOUBLE) || defined (PYTHON_SCAN)
 #include "int64x64-double.h"
 #elif defined (INT64X64_USE_CAIRO)
 #include "int64x64-cairo.h"