diff --git a/README.md b/README.md
index 5759d12..1b6d177 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 # toy Diffie-Hellman key exchange
-Uses 256-bit Sophie-Germain primes for stuff
+Uses 256-bit primes for stuff
 
 ```
 nix run git+https://git.pyrope.net/mbk/diffie-hellman
diff --git a/src/main.rs b/src/main.rs
index 4771a1f..467d3c4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -23,7 +23,7 @@ fn main() {
 
     println!("p = {p}, g = {g}");
 
-    let a: BigUint = rng.gen_safe_prime(256);
+    let a: BigUint = rng.gen_prime(256, None);
     println!("a = {a}");
 
     let ga = g.modpow(&a, &p);