diff --git a/internal/ceres/line_search.cc b/internal/ceres/line_search.cc
index 79c4393..039975d 100644
--- a/internal/ceres/line_search.cc
+++ b/internal/ceres/line_search.cc
@@ -43,6 +43,7 @@
 #include "absl/log/log.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
+#include "absl/time/clock.h"
 #include "absl/time/time.h"
 #include "ceres/evaluator.h"
 #include "ceres/function_sample.h"
diff --git a/internal/ceres/line_search_minimizer.cc b/internal/ceres/line_search_minimizer.cc
index 63a0d81..1f0b05b 100644
--- a/internal/ceres/line_search_minimizer.cc
+++ b/internal/ceres/line_search_minimizer.cc
@@ -51,6 +51,7 @@
 #include "absl/log/check.h"
 #include "absl/log/log.h"
 #include "absl/strings/str_format.h"
+#include "absl/time/clock.h"
 #include "absl/time/time.h"
 #include "ceres/array_utils.h"
 #include "ceres/evaluator.h"
diff --git a/internal/ceres/trust_region_minimizer.cc b/internal/ceres/trust_region_minimizer.cc
index 43b7ebb..068cc8d 100644
--- a/internal/ceres/trust_region_minimizer.cc
+++ b/internal/ceres/trust_region_minimizer.cc
@@ -43,6 +43,7 @@
 #include "absl/log/check.h"
 #include "absl/log/log.h"
 #include "absl/strings/str_format.h"
+#include "absl/time/clock.h"
 #include "absl/time/time.h"
 #include "ceres/array_utils.h"
 #include "ceres/coordinate_descent_minimizer.h"