diff --git a/include/gp_utils.h b/include/gp_utils.h
index 2f50c6f..a57220e 100755
--- a/include/gp_utils.h
+++ b/include/gp_utils.h
@@ -8,7 +8,6 @@
 #include <cstdlib>
 #include <cmath>
 #include <cassert>
-#include <tr1/cstdint>
 
 namespace libgp {
   
@@ -26,7 +25,7 @@ namespace libgp {
     /** Pseudorandom integers from a uniform discrete distribution.
      *  Returns a random integer drawn from the discrete uniform 
      *  distribution on 0, ..., n-1. */
-    static uint32_t randi(uint32_t n);
+    static size_t randi(size_t n);
     
     /** Double precision numerical approximation to the standard normal 
      *  cumulative distribution function. The cumulative standard normal 
diff --git a/src/gp_utils.cc b/src/gp_utils.cc
index 5340bd2..ce5f73e 100755
--- a/src/gp_utils.cc
+++ b/src/gp_utils.cc
@@ -29,7 +29,7 @@ namespace libgp {
     return array;
   }
   
-  uint32_t Utils::randi(uint32_t n) 
+  size_t Utils::randi(size_t n) 
   {
     return drand48()*n;
   }