diff --git a/compiler/rustc_infer/src/traits/project.rs b/compiler/rustc_infer/src/traits/project.rs
index 31ceb234332..c6ffba59638 100644
--- a/compiler/rustc_infer/src/traits/project.rs
+++ b/compiler/rustc_infer/src/traits/project.rs
@@ -78,11 +78,12 @@ pub struct ProjectionCacheStorage<'tcx> {
 #[derive(Copy, Clone, Debug, Hash, PartialEq, Eq)]
 pub struct ProjectionCacheKey<'tcx> {
     ty: ty::AliasTy<'tcx>,
+    param_env: ty::ParamEnv<'tcx>,
 }
 
 impl<'tcx> ProjectionCacheKey<'tcx> {
-    pub fn new(ty: ty::AliasTy<'tcx>) -> Self {
-        Self { ty }
+    pub fn new(ty: ty::AliasTy<'tcx>, param_env: ty::ParamEnv<'tcx>) -> Self {
+        Self { ty, param_env }
     }
 }
 
diff --git a/compiler/rustc_trait_selection/src/traits/fulfill.rs b/compiler/rustc_trait_selection/src/traits/fulfill.rs
index fbff78304ac..8cd9f39d5d8 100644
--- a/compiler/rustc_trait_selection/src/traits/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/traits/fulfill.rs
@@ -758,9 +758,9 @@ impl<'a, 'tcx> FulfillProcessor<'a, 'tcx> {
             // no type variables present, can use evaluation for better caching.
             // FIXME: consider caching errors too.
             if self.selcx.infcx.predicate_must_hold_considering_regions(obligation) {
-                if let Some(key) = ProjectionCacheKey::from_poly_projection_predicate(
+                if let Some(key) = ProjectionCacheKey::from_poly_projection_obligation(
                     &mut self.selcx,
-                    project_obligation.predicate,
+                    &project_obligation,
                 ) {
                     // If `predicate_must_hold_considering_regions` succeeds, then we've
                     // evaluated all sub-obligations. We can therefore mark the 'root'
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 67865bfcaa3..ca0b50864a8 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -344,7 +344,7 @@ pub(super) fn opt_normalize_projection_type<'a, 'b, 'tcx>(
     let use_cache = !selcx.is_intercrate();
 
     let projection_ty = infcx.resolve_vars_if_possible(projection_ty);
-    let cache_key = ProjectionCacheKey::new(projection_ty);
+    let cache_key = ProjectionCacheKey::new(projection_ty, param_env);
 
     // FIXME(#20304) For now, I am caching here, which is good, but it
     // means we don't capture the type variables that are created in
@@ -2105,27 +2105,28 @@ fn assoc_ty_own_obligations<'cx, 'tcx>(
 }
 
 pub(crate) trait ProjectionCacheKeyExt<'cx, 'tcx>: Sized {
-    fn from_poly_projection_predicate(
+    fn from_poly_projection_obligation(
         selcx: &mut SelectionContext<'cx, 'tcx>,
-        predicate: ty::PolyProjectionPredicate<'tcx>,
+        obligation: &PolyProjectionObligation<'tcx>,
     ) -> Option<Self>;
 }
 
 impl<'cx, 'tcx> ProjectionCacheKeyExt<'cx, 'tcx> for ProjectionCacheKey<'tcx> {
-    fn from_poly_projection_predicate(
+    fn from_poly_projection_obligation(
         selcx: &mut SelectionContext<'cx, 'tcx>,
-        predicate: ty::PolyProjectionPredicate<'tcx>,
+        obligation: &PolyProjectionObligation<'tcx>,
     ) -> Option<Self> {
         let infcx = selcx.infcx;
         // We don't do cross-snapshot caching of obligations with escaping regions,
         // so there's no cache key to use
-        predicate.no_bound_vars().map(|predicate| {
+        obligation.predicate.no_bound_vars().map(|predicate| {
             ProjectionCacheKey::new(
                 // We don't attempt to match up with a specific type-variable state
                 // from a specific call to `opt_normalize_projection_type` - if
                 // there's no precise match, the original cache entry is "stranded"
                 // anyway.
                 infcx.resolve_vars_if_possible(predicate.projection_ty),
+                obligation.param_env,
             )
         })
     }
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index 10370c7898b..fc12fed3537 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -815,7 +815,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                 // `EvaluatedToOkModuloRegions`), and skip re-evaluating the
                                 // sub-obligations.
                                 if let Some(key) =
-                                    ProjectionCacheKey::from_poly_projection_predicate(self, data)
+                                    ProjectionCacheKey::from_poly_projection_obligation(
+                                        self,
+                                        &project_obligation,
+                                    )
                                 {
                                     if let Some(cached_res) = self
                                         .infcx
@@ -844,8 +847,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                     && (eval_rslt == EvaluatedToOk
                                         || eval_rslt == EvaluatedToOkModuloRegions)
                                     && let Some(key) =
-                                        ProjectionCacheKey::from_poly_projection_predicate(
-                                            self, data,
+                                        ProjectionCacheKey::from_poly_projection_obligation(
+                                            self,
+                                            &project_obligation,
                                         )
                                 {
                                     // If the result is something that we can cache, then mark this