diff --git a/internal/ceres/preconditioner.h b/internal/ceres/preconditioner.h
index 5bb077e..894a2e6 100644
--- a/internal/ceres/preconditioner.h
+++ b/internal/ceres/preconditioner.h
@@ -70,7 +70,7 @@
     // For example if elimination_groups is a vector of size k, then
     // the linear solver is informed that it should eliminate the
     // parameter blocks 0 ... elimination_groups[0] - 1 first, and
-    // then elimination_groups[0] ... elimination_groups[1] and so
+    // then elimination_groups[0] ... elimination_groups[1] - 1 and so
     // on. Within each elimination group, the linear solver is free to
     // choose how the parameter blocks are ordered. Different linear
     // solvers have differing requirements on elimination_groups.