diff --git a/packages/babel-core/src/transformation/file/merge-map.js b/packages/babel-core/src/transformation/file/merge-map.js
index 50044580a1..991373862e 100644
--- a/packages/babel-core/src/transformation/file/merge-map.js
+++ b/packages/babel-core/src/transformation/file/merge-map.js
@@ -293,7 +293,7 @@ function findInsertionLocation<T>(
   // Ensure the value is the start of any set of matches.
   let i = left;
   if (i < array.length) {
-    while (i > 0 && callback(array[i]) >= 0) {
+    while (i >= 0 && callback(array[i]) >= 0) {
       i--;
     }
     return i + 1;