diff --git a/lib/bummr/bisecter.rb b/lib/bummr/bisecter.rb
index 394ce8f..38b78c3 100644
--- a/lib/bummr/bisecter.rb
+++ b/lib/bummr/bisecter.rb
@@ -5,12 +5,14 @@ class Bisecter
     def bisect
       puts "Bad commits found! Bisecting...".color(:red)
 
+      toplevel_path = `git rev-parse --show-toplevel`.chomp
+
       system("bundle")
-      system("git bisect start")
-      system("git bisect bad")
-      system("git bisect good #{BASE_BRANCH}")
+      system("git -C #{toplevel_path} bisect start")
+      system("git -C #{toplevel_path} bisect bad")
+      system("git -C #{toplevel_path} bisect good #{BASE_BRANCH}")
 
-      Open3.popen2e("git bisect run #{TEST_COMMAND}") do |_std_in, std_out_err|
+      Open3.popen2e("git -C #{toplevel_path} bisect run #{TEST_COMMAND}") do |_std_in, std_out_err|
         while line = std_out_err.gets
           puts line