diff --git a/tools/benchtool/03-analyze-benchmarks.rb b/tools/benchtool/03-analyze-benchmarks.rb
index 5a37df0b..91fffbbb 100755
--- a/tools/benchtool/03-analyze-benchmarks.rb
+++ b/tools/benchtool/03-analyze-benchmarks.rb
@@ -98,7 +98,7 @@ def generate_table rows
 }
 
 if File.exist?("target/criterion/commit.txt")
-    commit = `git rev-parse HEAD`.strip
+    commit = File.read("target/criterion/commit.txt")
     commit_known = true
 else
     commit = "master"