diff --git a/Cargo.toml b/Cargo.toml
index 72651da..162eb3b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ keywords = ["random", "c-api", "dsl"]
 
 [dependencies]
 rvs-parser = { version = "0.4", path = "parser" }
-rand = "0.4"
+rand = "0.5.0-pre.0"
 linked-hash-map = "0.5"
 
 [workspace]
diff --git a/src/transform/rand.rs b/src/transform/rand.rs
index 00217c4..5a92fe5 100644
--- a/src/transform/rand.rs
+++ b/src/transform/rand.rs
@@ -6,7 +6,7 @@ use rand::{self, Rng, SeedableRng};
 pub type CrateRng = rand::XorShiftRng;
 
 #[derive(Clone)]
-pub struct Seed([u32; 4]);
+pub struct Seed([u8; 16]);
 
 impl Seed {
     /// Generates a 128-bit seed from a 32-bit seed
@@ -34,7 +34,24 @@ impl Seed {
     }
 
     pub fn from_u32_array(x: [u32; 4]) -> Seed {
-        Seed(x)
+        Seed([
+             (x[0] >>  0) as u8,
+             (x[0] >>  8) as u8,
+             (x[0] >> 16) as u8,
+             (x[0] >> 24) as u8,
+             (x[1] >>  0) as u8,
+             (x[1] >>  8) as u8,
+             (x[1] >> 16) as u8,
+             (x[1] >> 24) as u8,
+             (x[2] >>  0) as u8,
+             (x[2] >>  8) as u8,
+             (x[2] >> 16) as u8,
+             (x[2] >> 24) as u8,
+             (x[3] >>  0) as u8,
+             (x[3] >>  8) as u8,
+             (x[3] >> 16) as u8,
+             (x[3] >> 24) as u8,
+        ])
     }
 
     pub fn to_rng(&self) -> CrateRng {
diff --git a/src/types/range.rs b/src/types/range.rs
index d255d1f..22638ad 100644
--- a/src/types/range.rs
+++ b/src/types/range.rs
@@ -2,8 +2,8 @@ use std::fmt;
 use std::u32;
 use rand::Rng;
 use rand::distributions::Range as RandRange;
-use rand::distributions::Sample;
-use rand::distributions::IndependentSample;
+use rand::distributions::{Sample, IndependentSample};
+use rand::distributions::range::RangeInt;
 
 use transform::CrateRng;
 use model::{Expr, ExprData};
@@ -18,7 +18,7 @@ pub struct Range {
 
 #[derive(Clone)]
 pub struct RandRangeInclusive {
-    range: RandRange<u32>,
+    range: RandRange<RangeInt<u32>>,
     use_range: bool,
     offset: bool,
 }
diff --git a/src/types/weighted.rs b/src/types/weighted.rs
index fcd022a..a42a780 100644
--- a/src/types/weighted.rs
+++ b/src/types/weighted.rs
@@ -3,6 +3,7 @@ use model::{Expr, ExprData};
 
 use rand::Rng;
 use rand::distributions::{Range, Sample};
+use rand::distributions::range::RangeInt;
 use std::fmt;
 
 #[derive(Clone)]
@@ -10,7 +11,7 @@ pub struct WeightedWithReplacement {
     data: ExprData,
     weights: Vec<u32>,
     children: Vec<Box<Expr>>,
-    range: Range<usize>,
+    range: Range<RangeInt<usize>>,
     pool: Vec<usize>,
     pool_index: Option<usize>,
 }