diff --git a/src/lib.rs b/src/lib.rs
index 11cbbde06a..f8410db4dd 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,6 +13,7 @@
 #![feature(lint_reasons)]
 #![feature(trait_upcasting)]
 #![feature(strict_overflow_ops)]
+#![feature(is_none_or)]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,
diff --git a/src/shims/foreign_items.rs b/src/shims/foreign_items.rs
index 898fc111fd..911958e558 100644
--- a/src/shims/foreign_items.rs
+++ b/src/shims/foreign_items.rs
@@ -396,12 +396,12 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     // If the newly promised alignment is bigger than the native alignment of this
                     // allocation, and bigger than the previously promised alignment, then set it.
                     if align > alloc_align
-                        && !this
+                        && this
                             .machine
                             .symbolic_alignment
                             .get_mut()
                             .get(&alloc_id)
-                            .is_some_and(|&(_, old_align)| align <= old_align)
+                            .is_none_or(|&(_, old_align)| align > old_align)
                     {
                         this.machine.symbolic_alignment.get_mut().insert(alloc_id, (offset, align));
                     }