diff --git a/sandboxed_api/sandbox2/examples/crc4/crc4sandbox.cc b/sandboxed_api/sandbox2/examples/crc4/crc4sandbox.cc
index b013ab3..ae64720 100644
--- a/sandboxed_api/sandbox2/examples/crc4/crc4sandbox.cc
+++ b/sandboxed_api/sandbox2/examples/crc4/crc4sandbox.cc
@@ -41,6 +41,8 @@
 #include "sandboxed_api/sandbox2/util/bpf_helper.h"
 #include "sandboxed_api/sandbox2/util/runfiles.h"
 
+using std::string;
+
 ABSL_FLAG(string, input, "", "Input to calculate CRC4 of.");
 ABSL_FLAG(bool, call_syscall_not_allowed, false,
           "Have sandboxee call clone (violation).");
diff --git a/sandboxed_api/sandbox2/examples/tool/sandbox2tool.cc b/sandboxed_api/sandbox2/examples/tool/sandbox2tool.cc
index 78e4c28..01624f3 100644
--- a/sandboxed_api/sandbox2/examples/tool/sandbox2tool.cc
+++ b/sandboxed_api/sandbox2/examples/tool/sandbox2tool.cc
@@ -44,6 +44,8 @@
 #include "sandboxed_api/sandbox2/util.h"
 #include "sandboxed_api/sandbox2/util/bpf_helper.h"
 
+using std::string;
+
 ABSL_FLAG(bool, sandbox2tool_keep_env, false,
           "Keep current environment variables");
 ABSL_FLAG(bool, sandbox2tool_redirect_fd1, false,
diff --git a/sandboxed_api/sandbox2/examples/zlib/zpipe_sandbox.cc b/sandboxed_api/sandbox2/examples/zlib/zpipe_sandbox.cc
index 2da7f9e..9ab7002 100644
--- a/sandboxed_api/sandbox2/examples/zlib/zpipe_sandbox.cc
+++ b/sandboxed_api/sandbox2/examples/zlib/zpipe_sandbox.cc
@@ -40,6 +40,8 @@
 #include "sandboxed_api/sandbox2/util/bpf_helper.h"
 #include "sandboxed_api/sandbox2/util/runfiles.h"
 
+using std::string;
+
 ABSL_FLAG(string, input, "", "Input file");
 ABSL_FLAG(string, output, "", "Output file");
 ABSL_FLAG(bool, decompress, false, "Decompress instead of compress.");
diff --git a/sandboxed_api/sandbox2/monitor.cc b/sandboxed_api/sandbox2/monitor.cc
index baf363b..38fa547 100644
--- a/sandboxed_api/sandbox2/monitor.cc
+++ b/sandboxed_api/sandbox2/monitor.cc
@@ -63,6 +63,8 @@
 #include "sandboxed_api/sandbox2/util.h"
 #include "sandboxed_api/util/raw_logging.h"
 
+using std::string;
+
 ABSL_FLAG(bool, sandbox2_report_on_sandboxee_signal, true,
           "Report sandbox2 sandboxee deaths caused by signals");
 
diff --git a/sandboxed_api/sandbox2/policy.cc b/sandboxed_api/sandbox2/policy.cc
index 05f467a..a2ca725 100644
--- a/sandboxed_api/sandbox2/policy.cc
+++ b/sandboxed_api/sandbox2/policy.cc
@@ -35,6 +35,8 @@
 #include "sandboxed_api/sandbox2/syscall.h"
 #include "sandboxed_api/sandbox2/util/bpf_helper.h"
 
+using std::string;
+
 ABSL_FLAG(bool, sandbox2_danger_danger_permit_all, false,
           "Allow all syscalls, useful for testing");
 ABSL_FLAG(string, sandbox2_danger_danger_permit_all_and_log, "",