diff --git a/include/vsmc/rng/counter.hpp b/include/vsmc/rng/counter.hpp
index 66819522d..7f26b96d7 100644
--- a/include/vsmc/rng/counter.hpp
+++ b/include/vsmc/rng/counter.hpp
@@ -362,6 +362,12 @@ class CounterEngine
             return;
         }
 
+        std::memcpy(
+            r, buffer_.data() + index_, sizeof(result_type) * (M_ - index_));
+        r += M_ - index_;
+        n -= M_ - index_;
+        index_ = M_;
+
         const std::size_t k = 1024 / M_;
         if (k != 0) {
             const std::size_t m = (n / M_) / k;
diff --git a/include/vsmc/rng/u01_distribution.hpp b/include/vsmc/rng/u01_distribution.hpp
index c7cf07495..6c1779441 100644
--- a/include/vsmc/rng/u01_distribution.hpp
+++ b/include/vsmc/rng/u01_distribution.hpp
@@ -107,8 +107,8 @@ inline void u01_distribution(RNGType &rng, std::size_t n, RealType *r)
     const std::size_t m = n / k;
     const std::size_t l = n % k;
     for (std::size_t i = 0; i != m; ++i, r += k)
-        internal::u01_distribution_impl<k, RealType>(rng, k, r);
-    internal::u01_distribution_impl<k, RealType>(rng, l, r);
+        internal::u01_distribution_impl<k>(rng, k, r);
+    internal::u01_distribution_impl<k>(rng, l, r);
 }
 
 VSMC_DEFINE_RNG_DISTRIBUTION_RAND_0(U01, u01, RealType)