diff --git a/compiler/rustc_mir/src/transform/coverage/mod.rs b/compiler/rustc_mir/src/transform/coverage/mod.rs
index 60757178bec..3ef03ec21ad 100644
--- a/compiler/rustc_mir/src/transform/coverage/mod.rs
+++ b/compiler/rustc_mir/src/transform/coverage/mod.rs
@@ -112,7 +112,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
         let source_file = source_map.lookup_source_file(body_span.lo());
         let fn_sig_span = match some_fn_sig.filter(|fn_sig| {
             fn_sig.span.ctxt() == body_span.ctxt()
-                && Lrc::ptr_eq(&source_file, &source_map.lookup_source_file(fn_sig.span.hi()))
+                && Lrc::ptr_eq(&source_file, &source_map.lookup_source_file(fn_sig.span.lo()))
         }) {
             Some(fn_sig) => fn_sig.span.with_hi(body_span.lo()),
             None => body_span.shrink_to_lo(),