diff --git a/src/qc_test.rs b/src/qc_test.rs
index bc76d65..1e02159 100644
--- a/src/qc_test.rs
+++ b/src/qc_test.rs
@@ -16,18 +16,18 @@ const KEY_RUN_LEN: usize = 8;
 const KEY_MAX_VAL: u8 = 4;
 
 impl Arbitrary for Key {
-    fn arbitrary<G: Gen>(g: &mut G) -> Key {
-        let len = g.gen::<usize>() % KEY_RUN_LEN;
+    fn arbitrary(g: &mut Gen) -> Key {
+        let len = usize::arbitrary(g) % KEY_RUN_LEN;
         let mut key = Vec::with_capacity(len);
         for _ in 0..len {
-            key.push(g.gen::<u8>() % KEY_MAX_VAL);
+            key.push(u8::arbitrary(g) % KEY_MAX_VAL);
         }
         Key(key)
     }
 }
 
 impl Key {
-    fn extend_random<G: Gen>(&self, g: &mut G) -> Key {
+    fn extend_random(&self, g: &mut Gen) -> Key {
         self.extend(Key::arbitrary(g))
     }
 
@@ -49,18 +49,18 @@ impl TrieKey for Key {
 }
 
 impl Arbitrary for RandomKeys {
-    fn arbitrary<G: Gen>(g: &mut G) -> RandomKeys {
-        let num_keys = g.gen::<usize>() % MAX_KEYS;
+    fn arbitrary(g: &mut Gen) -> RandomKeys {
+        let num_keys = usize::arbitrary(g) % MAX_KEYS;
         let mut keys = Vec::with_capacity(num_keys);
         keys.push(Key::arbitrary(g));
 
         for _ in 0..num_keys {
-            match g.gen::<u8>() % 10 {
+            match u8::arbitrary(g) % 10 {
                 // Generate a new random key.
                 1 => keys.push(Key::arbitrary(g)),
                 // Extend an existing key.
                 _ => {
-                    let i = g.gen::<usize>() % keys.len();
+                    let i = usize::arbitrary(g) % keys.len();
                     let key = keys[i].extend_random(g);
                     keys.push(key);
                 }