diff --git a/lib/prism/parse_result.rb b/lib/prism/parse_result.rb
index 05c14e33f5..3570af136a 100644
--- a/lib/prism/parse_result.rb
+++ b/lib/prism/parse_result.rb
@@ -155,21 +155,8 @@ def deep_freeze
     # Binary search through the offsets to find the line number for the given
     # byte offset.
     def find_line(byte_offset)
-      left = 0
-      right = offsets.length - 1
-
-      while left <= right
-        mid = left + (right - left) / 2
-        return mid if (offset = offsets[mid]) == byte_offset
-
-        if offset < byte_offset
-          left = mid + 1
-        else
-          right = mid - 1
-        end
-      end
-
-      left - 1
+      index = offsets.bsearch_index { |offset| offset > byte_offset } || offsets.length
+      index - 1
     end
   end