diff --git a/ci/miri.sh b/ci/miri.sh
index 2c91474..0ffbe96 100755
--- a/ci/miri.sh
+++ b/ci/miri.sh
@@ -9,4 +9,4 @@ rustup default "$MIRI_NIGHTLY"
 rustup component add miri
 cargo miri setup
 
-cargo miri test --all-features
+MIRIFLAGS='-Zmiri-strict-provenance' cargo miri test --all-features
diff --git a/src/traits.rs b/src/traits.rs
index a136306..4be2d2d 100644
--- a/src/traits.rs
+++ b/src/traits.rs
@@ -94,7 +94,9 @@ pub(crate) mod internal {
             U: Capacity,
         {
             // Convert to `String::into_raw_parts` once stabilized
-            let mut owned = ManuallyDrop::new(owned);
+            // We need to go through Vec here to get provenance for the entire allocation
+            // instead of just the initialized parts.
+            let mut owned = ManuallyDrop::new(owned.into_bytes());
             let (fat, cap) = U::store(owned.len(), owned.capacity());
 
             (