diff --git a/common/mock_http_fetcher.h b/common/mock_http_fetcher.h
index 0f04319..dec81b0 100644
--- a/common/mock_http_fetcher.h
+++ b/common/mock_http_fetcher.h
@@ -76,7 +76,7 @@
   void set_connect_timeout(int connect_timeout_seconds) override {}
   void set_max_retry_count(int max_retry_count) override {}
 
-  // Dummy: no bytes were downloaded.
+  // No bytes were downloaded in the mock class.
   size_t GetBytesDownloaded() override { return sent_size_; }
 
   // Begins the transfer if it hasn't already begun.
diff --git a/payload_consumer/payload_metadata.h b/payload_consumer/payload_metadata.h
index cc42253..8b36f53 100644
--- a/payload_consumer/payload_metadata.h
+++ b/payload_consumer/payload_metadata.h
@@ -63,7 +63,7 @@
   // |metadata_signature| (if present) or the metadata signature in payload
   // itself (if present). Returns ErrorCode::kSuccess on match or a suitable
   // error code otherwise. This method must be called before any part of the
-  // metadata is parsed so that a man-in-the-middle attack on the SSL connection
+  // metadata is parsed so that an on-path attack on the SSL connection
   // to the payload server doesn't exploit any vulnerability in the code that
   // parses the protocol buffer.
   ErrorCode ValidateMetadataSignature(
diff --git a/payload_generator/squashfs_filesystem.cc b/payload_generator/squashfs_filesystem.cc
index eb4fda3..6152d7d 100644
--- a/payload_generator/squashfs_filesystem.cc
+++ b/payload_generator/squashfs_filesystem.cc
@@ -275,7 +275,7 @@
     auto last = std::unique(zlib_blks.begin(), zlib_blks.end());
     zlib_blks.erase(last, zlib_blks.end());
 
-    // Sanity check. Make sure zlib blocks are not overlapping.
+    // Make sure zlib blocks are not overlapping.
     auto result = std::adjacent_find(
         zlib_blks.begin(),
         zlib_blks.end(),
diff --git a/payload_state.cc b/payload_state.cc
index 36ab32b..4945fe7 100644
--- a/payload_state.cc
+++ b/payload_state.cc
@@ -1058,7 +1058,7 @@
     stored_time = Time::FromInternalValue(stored_value);
   }
 
-  // Sanity check: If the time read from disk is in the future
+  // Validation check: If the time read from disk is in the future
   // (modulo some slack to account for possible NTP drift
   // adjustments), something is fishy and we should report and
   // reset.
@@ -1105,7 +1105,7 @@
     stored_delta = TimeDelta::FromInternalValue(stored_value);
   }
 
-  // Sanity-check: Uptime can never be greater than the wall-clock
+  // Validation check: Uptime can never be greater than the wall-clock
   // difference (modulo some slack). If it is, report and reset
   // to the wall-clock difference.
   TimeDelta diff = GetUpdateDuration() - stored_delta;
diff --git a/scripts/brillo_update_payload b/scripts/brillo_update_payload
index 4b581fb..9bae74e 100755
--- a/scripts/brillo_update_payload
+++ b/scripts/brillo_update_payload
@@ -896,7 +896,7 @@
   check_update_payload ${PAYCHECK_ARGS[@]} --check
 }
 
-# Sanity check that the real generator exists:
+# Check that the real generator exists:
 [[ -x "${GENERATOR}" ]] || GENERATOR="$(which delta_generator || true)"
 [[ -x "${GENERATOR}" ]] || die "can't find delta_generator"
 
diff --git a/update_manager/chromeos_policy.cc b/update_manager/chromeos_policy.cc
index 8ea892e..be5f914 100644
--- a/update_manager/chromeos_policy.cc
+++ b/update_manager/chromeos_policy.cc
@@ -598,7 +598,6 @@
     string* error,
     UpdateBackoffAndDownloadUrlResult* result,
     const UpdateState& update_state) const {
-  // Sanity checks.
   DCHECK_GE(update_state.download_errors_max, 0);
 
   // Set default result values.
@@ -670,7 +669,7 @@
   Time prev_err_time;
   bool is_first = true;
   for (const auto& err_tuple : update_state.download_errors) {
-    // Do some sanity checks.
+    // Do some validation checks.
     int used_url_idx = get<0>(err_tuple);
     if (is_first && url_idx >= 0 && used_url_idx != url_idx) {
       LOG(WARNING) << "First URL in error log (" << used_url_idx