diff --git a/.github/actions/install-rust/action.yml b/.github/actions/install-rust/action.yml
index 2a350f248c..c5f40462ac 100644
--- a/.github/actions/install-rust/action.yml
+++ b/.github/actions/install-rust/action.yml
@@ -23,7 +23,7 @@ runs:
         elif [ "${{ inputs.toolchain }}" = "msrv" ]; then
           echo "version=1.$msrv.0" >> "$GITHUB_OUTPUT"
         elif [ "${{ inputs.toolchain }}" = "wasmtime-ci-pinned-nightly" ]; then
-          echo "version=nightly-2024-07-25" >> "$GITHUB_OUTPUT"
+          echo "version=nightly-2024-08-12" >> "$GITHUB_OUTPUT"
         else
           echo "version=${{ inputs.toolchain }}" >> "$GITHUB_OUTPUT"
         fi
diff --git a/crates/wasmtime/src/runtime/store.rs b/crates/wasmtime/src/runtime/store.rs
index e3e9f0f72c..e3dbe894c7 100644
--- a/crates/wasmtime/src/runtime/store.rs
+++ b/crates/wasmtime/src/runtime/store.rs
@@ -1178,13 +1178,14 @@ impl<T> StoreInner<T> {
 
         // Temporarily take the configured behavior to avoid mutably borrowing
         // multiple times.
+        #[cfg_attr(not(feature = "call-hook"), allow(unreachable_patterns))]
         if let Some(mut call_hook) = self.call_hook.take() {
             let result = self.invoke_call_hook(&mut call_hook, s);
             self.call_hook = Some(call_hook);
-            result
-        } else {
-            Ok(())
+            return result;
         }
+
+        Ok(())
     }
 
     fn invoke_call_hook(&mut self, call_hook: &mut CallHookInner<T>, s: CallHook) -> Result<()> {
diff --git a/crates/wasmtime/src/runtime/values.rs b/crates/wasmtime/src/runtime/values.rs
index 44244d2687..9d1c3bd3e5 100644
--- a/crates/wasmtime/src/runtime/values.rs
+++ b/crates/wasmtime/src/runtime/values.rs
@@ -854,9 +854,10 @@ impl Ref {
             (Ref::Any(_), HeapType::Any) => true,
             (Ref::Any(Some(a)), HeapType::I31) => a._is_i31(store)?,
             (Ref::Any(Some(a)), HeapType::Struct) => a._is_struct(store)?,
-            (Ref::Any(Some(a)), HeapType::ConcreteStruct(ty)) => match a._as_struct(store)? {
+            (Ref::Any(Some(a)), HeapType::ConcreteStruct(_ty)) => match a._as_struct(store)? {
                 None => false,
-                Some(s) => s._matches_ty(store, ty)?,
+                #[cfg_attr(not(feature = "gc"), allow(unreachable_patterns))]
+                Some(s) => s._matches_ty(store, _ty)?,
             },
             (Ref::Any(Some(_)), HeapType::Eq) => todo!("eqref"),
             (Ref::Any(Some(_)), HeapType::Array) => todo!("wasm GC arrays"),
diff --git a/crates/wasmtime/src/runtime/vm/cow.rs b/crates/wasmtime/src/runtime/vm/cow.rs
index 5a458d7fc5..ded449f8e3 100644
--- a/crates/wasmtime/src/runtime/vm/cow.rs
+++ b/crates/wasmtime/src/runtime/vm/cow.rs
@@ -1,6 +1,10 @@
 //! Copy-on-write initialization support: creation of backing images for
 //! modules, and logic to support mapping these backing images into memory.
 
+// `MemoryImageSource` is an empty enum on some platforms which triggers some
+// warnings
+#![cfg_attr(any(not(unix), miri), allow(unreachable_patterns))]
+
 use crate::prelude::*;
 use crate::runtime::vm::sys::vm::{self, MemoryImageSource};
 use crate::runtime::vm::{MmapVec, SendSyncPtr};
diff --git a/crates/wasmtime/src/runtime/vm/gc.rs b/crates/wasmtime/src/runtime/vm/gc.rs
index eee0509dee..e3d85f6467 100644
--- a/crates/wasmtime/src/runtime/vm/gc.rs
+++ b/crates/wasmtime/src/runtime/vm/gc.rs
@@ -149,6 +149,7 @@ impl GcStore {
     ) -> Result<Result<VMExternRef, Box<dyn Any + Send + Sync>>> {
         let host_data_id = self.host_data_table.alloc(value);
         match self.gc_heap.alloc_externref(host_data_id)? {
+            #[cfg_attr(not(feature = "gc"), allow(unreachable_patterns))]
             Some(x) => Ok(Ok(x)),
             None => Ok(Err(self.host_data_table.dealloc(host_data_id))),
         }