diff --git a/tig-challenges/Cargo.toml b/tig-challenges/Cargo.toml
index 2d0f9f9..290a0ad 100644
--- a/tig-challenges/Cargo.toml
+++ b/tig-challenges/Cargo.toml
@@ -13,7 +13,10 @@ cudarc = { version = "0.12.0", features = [
     "cuda-version-from-build-system",
 ], optional = true }
 ndarray = "0.15.6"
-rand = { version = "0.8.5", default-features = false, features = ["std_rng"] }
+rand = { version = "0.8.5", default-features = false, features = [
+    "std_rng",
+    "small_rng",
+] }
 serde = { version = "1.0.196", features = ["derive"] }
 serde_json = { version = "1.0.113" }
 
diff --git a/tig-challenges/src/lib.rs b/tig-challenges/src/lib.rs
index 42b27e1..5b30761 100644
--- a/tig-challenges/src/lib.rs
+++ b/tig-challenges/src/lib.rs
@@ -1,5 +1,5 @@
 use anyhow::{anyhow, Result};
-use rand::{rngs::StdRng, Rng, SeedableRng};
+use rand::{rngs::SmallRng, SeedableRng};
 use serde::de::DeserializeOwned;
 use serde::Serialize;
 
@@ -95,18 +95,18 @@ pub struct CudaKernel {
 }
 
 pub struct RngArray {
-    rngs: [StdRng; 8],
-    index: u32,
+    rngs: [SmallRng; 8],
+    index: usize,
 }
 
 impl RngArray {
     pub fn new(seeds: [u64; 8]) -> Self {
-        let rngs = seeds.map(StdRng::seed_from_u64);
+        let rngs = seeds.map(SmallRng::seed_from_u64);
         RngArray { rngs, index: 0 }
     }
 
-    pub fn get_mut(&mut self) -> &mut StdRng {
-        self.index = (&mut self.rngs[self.index as usize]).gen_range(0..8);
-        &mut self.rngs[self.index as usize]
+    pub fn get_mut(&mut self) -> &mut SmallRng {
+        self.index = (self.index + 1) % 8;
+        &mut self.rngs[self.index]
     }
 }