diff --git a/source/common/formatter/substitution_formatter.cc b/source/common/formatter/substitution_formatter.cc
index 4400ca3f6510..aedc72ad87e1 100644
--- a/source/common/formatter/substitution_formatter.cc
+++ b/source/common/formatter/substitution_formatter.cc
@@ -424,7 +424,7 @@ class StreamInfoDurationFieldExtractor : public StreamInfoFormatter::FieldExtrac
   }
 
 private:
-  absl::optional<uint32_t> extractMillis(const StreamInfo::StreamInfo& stream_info) const {
+  absl::optional<int64_t> extractMillis(const StreamInfo::StreamInfo& stream_info) const {
     const auto time = field_extractor_(stream_info);
     if (time) {
       return std::chrono::duration_cast<std::chrono::milliseconds>(time.value()).count();
diff --git a/source/common/grpc/google_async_client_impl.h b/source/common/grpc/google_async_client_impl.h
index f2dc3eded14d..75229bd5905f 100644
--- a/source/common/grpc/google_async_client_impl.h
+++ b/source/common/grpc/google_async_client_impl.h
@@ -255,7 +255,7 @@ class GoogleAsyncStreamImpl : public RawAsyncStream,
     // End-of-stream with no additional message.
     PendingMessage() = default;
 
-    const absl::optional<grpc::ByteBuffer> buf_;
+    const absl::optional<grpc::ByteBuffer> buf_{};
     const bool end_stream_{true};
   };
 
diff --git a/source/common/upstream/outlier_detection_impl.h b/source/common/upstream/outlier_detection_impl.h
index ff42473f3cc0..c51cb134bfbf 100644
--- a/source/common/upstream/outlier_detection_impl.h
+++ b/source/common/upstream/outlier_detection_impl.h
@@ -41,7 +41,7 @@ class DetectorHostMonitorNullImpl : public DetectorHostMonitor {
   double successRate(SuccessRateMonitorType) const override { return -1; }
 
 private:
-  const absl::optional<MonotonicTime> time_;
+  const absl::optional<MonotonicTime> time_{};
 };
 
 /**
diff --git a/source/extensions/common/aws/credentials_provider.h b/source/extensions/common/aws/credentials_provider.h
index ed6bb312561c..7e1da55fb182 100644
--- a/source/extensions/common/aws/credentials_provider.h
+++ b/source/extensions/common/aws/credentials_provider.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <memory>
 #include <string>
 
 #include "envoy/common/pure.h"
diff --git a/source/extensions/filters/http/grpc_http1_reverse_bridge/filter.cc b/source/extensions/filters/http/grpc_http1_reverse_bridge/filter.cc
index 972b31275ff6..d13b360ee07f 100644
--- a/source/extensions/filters/http/grpc_http1_reverse_bridge/filter.cc
+++ b/source/extensions/filters/http/grpc_http1_reverse_bridge/filter.cc
@@ -140,7 +140,7 @@ Http::FilterHeadersStatus Filter::encodeHeaders(Http::ResponseHeaderMap& headers
       headers.setGrpcStatus(Envoy::Grpc::Status::WellKnownGrpcStatus::Unknown);
       headers.setStatus(enumToInt(Http::Code::OK));
 
-      if (content_type != nullptr) {
+      if (!content_type.empty()) {
         headers.setContentType(content_type_);
       }
 
diff --git a/tools/type_whisperer/api_type_db.h b/tools/type_whisperer/api_type_db.h
index d5ee2dc7a324..cec5627588ea 100644
--- a/tools/type_whisperer/api_type_db.h
+++ b/tools/type_whisperer/api_type_db.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <string>
 #include <unordered_map>
 
 #include "absl/strings/string_view.h"