diff --git a/proptest-state-machine/src/strategy.rs b/proptest-state-machine/src/strategy.rs
index 15abfb44..d13c39c4 100644
--- a/proptest-state-machine/src/strategy.rs
+++ b/proptest-state-machine/src/strategy.rs
@@ -102,13 +102,13 @@ pub trait ReferenceStateMachine {
         BoxedStrategy<Self::State>,
         BoxedStrategy<Self::Transition>,
     > {
-        Sequential {
-            size: size.into(),
-            init_state: Self::init_state,
-            preconditions: Self::preconditions,
-            transitions: Self::transitions,
-            next: Self::apply,
-        }
+        Sequential::new(
+            size.into(),
+            Self::init_state,
+            Self::preconditions,
+            Self::transitions,
+            Self::apply,
+        )
     }
 }
 
@@ -146,6 +146,26 @@ pub struct Sequential<State, Transition, StateStrategy, TransitionStrategy> {
     next: fn(state: State, transition: &Transition) -> State,
 }
 
+impl<State, Transition, StateStrategy, TransitionStrategy>
+    Sequential<State, Transition, StateStrategy, TransitionStrategy>
+{
+    pub fn new(
+        size: SizeRange,
+        init_state: fn() -> StateStrategy,
+        preconditions: fn(state: &State, transition: &Transition) -> bool,
+        transitions: fn(state: &State) -> TransitionStrategy,
+        next: fn(state: State, transition: &Transition) -> State,
+    ) -> Self {
+        Self {
+            size,
+            init_state,
+            preconditions,
+            transitions,
+            next,
+        }
+    }
+}
+
 impl<State, Transition, StateStrategy, TransitionStrategy> Debug
     for Sequential<State, Transition, StateStrategy, TransitionStrategy>
 {
diff --git a/proptest/src/strategy/flatten.rs b/proptest/src/strategy/flatten.rs
index 63ac4160..89b8ebd9 100644
--- a/proptest/src/strategy/flatten.rs
+++ b/proptest/src/strategy/flatten.rs
@@ -261,7 +261,7 @@ impl<S: Strategy, R: Strategy, F: Fn(S::Value) -> R> Strategy
 mod test {
     use super::*;
 
-    use std::u32;
+    use std::u64;
 
     use crate::strategy::just::Just;
     use crate::test_runner::Config;
@@ -276,7 +276,7 @@ mod test {
         let mut failures = 0;
         let mut runner = TestRunner::new_with_rng(
             Config {
-                max_shrink_iters: u32::MAX - 1,
+                max_shrink_iters: u64::MAX - 1,
                 ..Config::default()
             },
             TestRng::deterministic_rng(RngAlgorithm::default()),
diff --git a/proptest/src/test_runner/config.rs b/proptest/src/test_runner/config.rs
index 0a5dc1c8..8eec88ae 100644
--- a/proptest/src/test_runner/config.rs
+++ b/proptest/src/test_runner/config.rs
@@ -118,7 +118,7 @@ pub fn contextualize_config(mut result: Config) -> Config {
             MAX_SHRINK_ITERS => parse_or_warn(
                 &value,
                 &mut result.max_shrink_iters,
-                "u32",
+                "u64",
                 MAX_SHRINK_ITERS,
             ),
             MAX_DEFAULT_SIZE_RANGE => parse_or_warn(
@@ -170,7 +170,7 @@ fn default_default_config() -> Config {
         timeout: 0,
         #[cfg(feature = "std")]
         max_shrink_time: 0,
-        max_shrink_iters: u32::MAX,
+        max_shrink_iters: u64::MAX,
         max_default_size_range: 100,
         result_cache: noop_result_cache,
         #[cfg(feature = "std")]
@@ -336,10 +336,10 @@ pub struct Config {
     /// Note that the type of this field will change in a future version of
     /// proptest to better accommodate its special values.
     ///
-    /// The default is `std::u32::MAX`, which can be overridden by setting the
+    /// The default is `std::u64::MAX`, which can be overridden by setting the
     /// `PROPTEST_MAX_SHRINK_ITERS` environment variable. (The variable is only
     /// considered when the `std` feature is enabled, which it is by default.)
-    pub max_shrink_iters: u32,
+    pub max_shrink_iters: u64,
 
     /// The default maximum size to `proptest::collection::SizeRange`. The default
     /// strategy for collections (like `Vec`) use collections in the range of
@@ -512,9 +512,9 @@ impl Config {
     /// Returns the configured limit on shrinking iterations.
     ///
     /// This takes into account the special "automatic" behaviour.
-    pub fn max_shrink_iters(&self) -> u32 {
-        if u32::MAX == self.max_shrink_iters {
-            self.cases.saturating_mul(4)
+    pub fn max_shrink_iters(&self) -> u64 {
+        if u64::MAX == self.max_shrink_iters {
+            (self.cases as u64).saturating_mul(4)
         } else {
             self.max_shrink_iters
         }