diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 89d0f34b47617..a6e4fd349fefe 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -277,7 +277,7 @@ fn make_code_region(
     if span.hi() == span.lo() {
         // Extend an empty span by one character so the region will be counted.
         if span.hi() == body_span.hi() {
-            start_col = start_col.saturating_sub(1);
+            start_col = start_col.saturating_sub(1).max(1);
         } else {
             end_col = start_col + 1;
         }