diff --git a/src/random_number_generator.h b/src/random_number_generator.h
index 9072618f8d..b9cbf2cca0 100644
--- a/src/random_number_generator.h
+++ b/src/random_number_generator.h
@@ -179,7 +179,7 @@ class ExponentialDoubleDist : public DoubleDistribution {
 };
 
 
-/// Binary distribution requires twp options and a probability
+/// Binary distribution requires two options and a probability
 class BinaryDoubleDist : public DoubleDistribution {
   private:
     boost::random::binomial_distribution<int> dist;