diff --git a/compiler/rustc_borrowck/src/dataflow.rs b/compiler/rustc_borrowck/src/dataflow.rs
index 94939c7e4cd72..167f245361a22 100644
--- a/compiler/rustc_borrowck/src/dataflow.rs
+++ b/compiler/rustc_borrowck/src/dataflow.rs
@@ -328,7 +328,7 @@ impl<'tcx> rustc_mir_dataflow::AnalysisDomain<'tcx> for Borrows<'_, 'tcx> {
 
     fn bottom_value(&self, _: &mir::Body<'tcx>) -> Self::Domain {
         // bottom = nothing is reserved or activated yet;
-        BitSet::new_empty(self.borrow_set.len() * 2)
+        BitSet::new_empty(self.borrow_set.len())
     }
 
     fn initialize_start_block(&self, _: &mir::Body<'tcx>, _: &mut Self::Domain) {