diff --git a/dhcp/Cargo.toml b/dhcp/Cargo.toml
index 312c523d..e0eaaaca 100644
--- a/dhcp/Cargo.toml
+++ b/dhcp/Cargo.toml
@@ -23,7 +23,7 @@ log = { version = "0.4", optional = true }
 
 [dev-dependencies]
 dhcproto = "0.12"
-rand_core = { version = "0.6", features = ["getrandom"] }
+rand_core = { version = "0.9", features = ["os_rng"] }
 stderrlog = "0.6"
 w5500-hl.path = "../hl"
 w5500-regsim.path = "../regsim"
diff --git a/dhcp/src/lib.rs b/dhcp/src/lib.rs
index eeffa5e7..b11b5656 100644
--- a/dhcp/src/lib.rs
+++ b/dhcp/src/lib.rs
@@ -78,7 +78,7 @@ pub enum State {
 /// # Example
 ///
 /// ```no_run
-/// use rand_core::RngCore;
+/// use rand_core::TryRngCore;
 /// use w5500_dhcp::{
 ///     ll::{net::Eui48Addr, Sn},
 ///     Client, Hostname,
@@ -97,7 +97,7 @@ pub enum State {
 ///
 /// this_is_where_you_setup_the_w5500_int_pin_for_a_falling_edge_trigger();
 ///
-/// let seed: u64 = rng.next_u64();
+/// let seed: u64 = rng.try_next_u64().unwrap();
 ///
 /// let mut dhcp: Client = Client::new(DHCP_SN, seed, MAC_ADDRESS, HOSTNAME);
 ///
@@ -156,7 +156,7 @@ impl<'a> Client<'a> {
     /// # Example
     ///
     /// ```
-    /// use rand_core::RngCore;
+    /// use rand_core::TryRngCore;
     /// use w5500_dhcp::{
     ///     ll::{net::Eui48Addr, Sn},
     ///     Client, Hostname,
@@ -167,7 +167,7 @@ impl<'a> Client<'a> {
     /// // locally administered MAC address
     /// const MAC_ADDRESS: Eui48Addr = Eui48Addr::new(0x02, 0x00, 0x11, 0x22, 0x33, 0x44);
     /// const HOSTNAME: Hostname = Hostname::new_unwrapped("example");
-    /// let seed: u64 = rng.next_u64();
+    /// let seed: u64 = rng.try_next_u64().unwrap();
     ///
     /// let dhcp: Client = Client::new(DHCP_SN, seed, MAC_ADDRESS, HOSTNAME);
     /// ```
@@ -206,7 +206,7 @@ impl<'a> Client<'a> {
     /// Set a 10 second timeout.
     ///
     /// ```
-    /// use rand_core::RngCore;
+    /// use rand_core::TryRngCore;
     /// use w5500_dhcp::{
     ///     ll::{net::Eui48Addr, Sn},
     ///     Client, Hostname,
@@ -216,7 +216,7 @@ impl<'a> Client<'a> {
     /// const HOSTNAME: Hostname = Hostname::new_unwrapped("example");
     /// let mut dhcp: Client = Client::new(
     ///     Sn::Sn0,
-    ///     rng.next_u64(),
+    ///     rng.try_next_u64().unwrap(),
     ///     Eui48Addr::new(0x02, 0x00, 0x11, 0x22, 0x33, 0x44),
     ///     HOSTNAME,
     /// );
@@ -231,7 +231,7 @@ impl<'a> Client<'a> {
     /// # Example
     ///
     /// ```
-    /// use rand_core::RngCore;
+    /// use rand_core::TryRngCore;
     /// use w5500_dhcp::{
     ///     ll::{net::Eui48Addr, Sn},
     ///     Client, Hostname,
@@ -241,7 +241,7 @@ impl<'a> Client<'a> {
     /// const HOSTNAME: Hostname = Hostname::new_unwrapped("example");
     /// let dhcp: Client = Client::new(
     ///     Sn::Sn0,
-    ///     rng.next_u64(),
+    ///     rng.try_next_u64().unwrap(),
     ///     Eui48Addr::new(0x02, 0x00, 0x11, 0x22, 0x33, 0x44),
     ///     HOSTNAME,
     /// );
diff --git a/dns/Cargo.toml b/dns/Cargo.toml
index ec0247cf..d7cf504f 100644
--- a/dns/Cargo.toml
+++ b/dns/Cargo.toml
@@ -23,7 +23,7 @@ log = { version = "0.4", optional = true }
 
 [dev-dependencies]
 log = "0.4"
-rand_core = { version = "0.6", features = ["getrandom"] }
+rand_core = { version = "0.9", features = ["os_rng"] }
 stderrlog = "0.6"
 w5500-regsim.path = "../regsim"
 
diff --git a/dns/examples/simple.rs b/dns/examples/simple.rs
index 8e93ff5b..2a02945a 100644
--- a/dns/examples/simple.rs
+++ b/dns/examples/simple.rs
@@ -4,7 +4,7 @@
 //!
 //! **Note:** This will communicate with external network services.
 
-use rand_core::{OsRng, RngCore};
+use rand_core::{OsRng, TryRngCore};
 use std::time::{Duration, Instant};
 use w5500_dns::{
     hl::{Error, Udp},
@@ -34,7 +34,9 @@ fn main() {
         .udp_bind(DNS_SOCKET, DNS_SOURCE_PORT)
         .expect("failed to bind");
 
-    let random_number: u64 = OsRng.next_u64();
+    let random_number: u64 = OsRng
+        .try_next_u64()
+        .expect("Failed to generate random number");
 
     let mut dns_client: Client = Client::new(
         Sn::Sn3,
diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
index 167b8ed8..af467747 100644
--- a/fuzz/Cargo.toml
+++ b/fuzz/Cargo.toml
@@ -6,5 +6,5 @@ publish = false
 edition = "2021"
 
 [dependencies]
-rand_core = "0.6"
+rand_core = { version = "0.9", features = ["os_rng"] }
 w5500-ll.path = "../ll"
diff --git a/fuzz/src/lib.rs b/fuzz/src/lib.rs
index 5ed2d750..65c2eae8 100644
--- a/fuzz/src/lib.rs
+++ b/fuzz/src/lib.rs
@@ -108,12 +108,6 @@ impl rand_core::RngCore for NotRng {
     fn fill_bytes(&mut self, dest: &mut [u8]) {
         dest.iter_mut().for_each(|b| *b = self.next_byte());
     }
-
-    #[inline]
-    fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), rand_core::Error> {
-        dest.iter_mut().for_each(|b| *b = self.next_byte());
-        Ok(())
-    }
 }
 
 impl rand_core::CryptoRng for NotRng {}
diff --git a/testsuite/Cargo.toml b/testsuite/Cargo.toml
index b33ff78a..22ef5fac 100644
--- a/testsuite/Cargo.toml
+++ b/testsuite/Cargo.toml
@@ -8,7 +8,7 @@ edition = "2021"
 [dependencies]
 ftdi-embedded-hal = { version = "0.22.0", features = ["libftd2xx", "libftd2xx-static"] }
 log = "0.4"
-rand_core = { version = "0.6.3", features = ["getrandom"] }
+rand_core = { version = "0.6", features = ["getrandom"] }
 stderrlog = "0.6"
 
 w5500-dhcp = { path = "../dhcp", features = ["eh1", "log"] }
diff --git a/tls/afl/Cargo.toml b/tls/afl/Cargo.toml
index f3ad2fe4..38233c26 100644
--- a/tls/afl/Cargo.toml
+++ b/tls/afl/Cargo.toml
@@ -7,7 +7,7 @@ edition = "2021"
 
 [dependencies]
 afl = "0.15"
-rand_core = "0.6"
+rand_core = "0.9"
 stderrlog = "0.6"
 w5500-fuzz.path = "../../fuzz"
 w5500-regsim.path = "../../regsim"