diff --git a/oss-internship-2020/libtiff/example/main_sandboxed.cc b/oss-internship-2020/libtiff/example/main_sandboxed.cc
index 0dec1ff..5ab32cc 100644
--- a/oss-internship-2020/libtiff/example/main_sandboxed.cc
+++ b/oss-internship-2020/libtiff/example/main_sandboxed.cc
@@ -171,8 +171,8 @@ absl::Status LibTIFFMain(const std::string& srcfile) {
 
   TiffSapiSandbox sandbox(srcfile);
 
-  bool pixel_status = true;
-  bool cluster_status = true;
+  bool pixel_status_ok = true;
+  bool cluster_status_ok = true;
   // initialize sapi vars after constructing TiffSapiSandbox
   sapi::v::UShort h;
   sapi::v::UShort v;
@@ -226,10 +226,10 @@ absl::Status LibTIFFMain(const std::string& srcfile) {
     if (status = CheckCluster(id, buffer_, data); !status.ok()) {
       LOG(ERROR) << "CheckCluster failed:\n" << status.ToString();
     }
-    cluster_status &= status.ok();
+    cluster_status_ok &= status.ok();
   }
 
-  if (!cluster_status) {
+  if (!cluster_status_ok) {
     return absl::InternalError("One or more clusters failed the check");
   }
 
@@ -262,7 +262,7 @@ absl::Status LibTIFFMain(const std::string& srcfile) {
     if (status = CheckRgbPixel(id, data, buffer2_); !status.ok()) {
       LOG(ERROR) << "CheckRgbPixel failed:\n" << status.ToString();
     }
-    pixel_status &= status.ok();
+    pixel_status_ok &= status.ok();
   }
 
   SAPI_RETURN_IF_ERROR(api.TIFFClose(&tif));
@@ -290,12 +290,12 @@ absl::Status LibTIFFMain(const std::string& srcfile) {
     if (status = CheckRgbaPixel(id, data, rgba_buffer_); !status.ok()) {
       LOG(ERROR) << "CheckRgbaPixel failed:\n" << status.ToString();
     }
-    pixel_status &= status.ok();
+    pixel_status_ok &= status.ok();
   }
 
   SAPI_RETURN_IF_ERROR(api.TIFFClose(&tif2));
 
-  if (!pixel_status) {
+  if (!pixel_status_ok) {
     return absl::InternalError("wrong encoding");
   }
 
diff --git a/oss-internship-2020/libtiff/test/long_tag.cc b/oss-internship-2020/libtiff/test/long_tag.cc
index fc1b644..1c7d75d 100644
--- a/oss-internship-2020/libtiff/test/long_tag.cc
+++ b/oss-internship-2020/libtiff/test/long_tag.cc
@@ -101,7 +101,7 @@ TEST(SandboxTest, LongTag) {
   EXPECT_THAT(status_or_int.value(), IsTrue())
       << "Can't set PhotometricInterpretation tag";
 
-  for (auto& tag : kLongTags) {
+  for (const auto& tag : kLongTags) {
     status_or_int = api.TIFFSetFieldU1(&tif, tag.tag, tag.value);
     ASSERT_THAT(status_or_int, IsOk()) << "TIFFSetFieldUShort1 fatal error";
     EXPECT_THAT(status_or_int.value(), IsTrue()) << "Can't set tag " << tag.tag;
@@ -125,7 +125,7 @@ TEST(SandboxTest, LongTag) {
   CheckLongField(api, tif2, TIFFTAG_IMAGELENGTH, kLength);
   CheckLongField(api, tif2, TIFFTAG_ROWSPERSTRIP, kRowsPerStrip);
 
-  for (auto& tag : kLongTags) {
+  for (const auto& tag : kLongTags) {
     CheckLongField(api, tif2, tag.tag, tag.value);
   }
 
diff --git a/oss-internship-2020/libtiff/test/short_tag.cc b/oss-internship-2020/libtiff/test/short_tag.cc
index 5620ec5..7f1c0d6 100644
--- a/oss-internship-2020/libtiff/test/short_tag.cc
+++ b/oss-internship-2020/libtiff/test/short_tag.cc
@@ -123,13 +123,13 @@ TEST(SandboxTest, ShortTag) {
   EXPECT_THAT(status_or_int.value(), IsTrue())
       << "Can't set PhotometricInterpretation tag";
 
-  for (auto& tag : kShortSingleTags) {
+  for (const auto& tag : kShortSingleTags) {
     status_or_int = api.TIFFSetFieldUShort1(&tif, tag.tag, tag.value);
     ASSERT_THAT(status_or_int, IsOk()) << "TIFFSetFieldUShort1 fatal error";
     EXPECT_THAT(status_or_int.value(), IsTrue()) << "Can't set tag " << tag.tag;
   }
 
-  for (auto& tag : kShortPairedTags) {
+  for (const auto& tag : kShortPairedTags) {
     status_or_int =
         api.TIFFSetFieldUShort2(&tif, tag.tag, tag.values[0], tag.values[1]);
     ASSERT_THAT(status_or_int, IsOk()) << "TIFFSetFieldUShort2 fatal error";
@@ -158,11 +158,11 @@ TEST(SandboxTest, ShortTag) {
   CheckLongField(api, tif2, TIFFTAG_ROWSPERSTRIP, kRowsPerStrip);
   CheckShortField(api, tif2, TIFFTAG_PLANARCONFIG, kPlanarConfig);
 
-  for (auto& tag : kShortSingleTags) {
+  for (const auto& tag : kShortSingleTags) {
     CheckShortField(api, tif2, tag.tag, tag.value);
   }
 
-  for (auto& tag : kShortPairedTags) {
+  for (const auto& tag : kShortPairedTags) {
     CheckShortPairedField(api, tif2, tag.tag, tag.values);
   }