diff --git a/pw_log/log.proto b/pw_log/log.proto
index aa45583aa1..a1f4e7011d 100644
--- a/pw_log/log.proto
+++ b/pw_log/log.proto
@@ -201,7 +201,7 @@ message FilterRule {
   Action action = 4;
 
   // Condition 4: (thread_equals.size() == 0 || log.thread == thread_equals).
-  optional bytes thread_equals = 5 [(tokenizer.format) = TOKENIZATION_OPTIONAL];
+  bytes thread_equals = 5 [(tokenizer.format) = TOKENIZATION_OPTIONAL];
 }
 
 // A filter is a series of rules. First matching rule wins.
diff --git a/pw_log_rpc/public/pw_log_rpc/log_filter_service.h b/pw_log_rpc/public/pw_log_rpc/log_filter_service.h
index bb074afbdb..3532ef2b89 100644
--- a/pw_log_rpc/public/pw_log_rpc/log_filter_service.h
+++ b/pw_log_rpc/public/pw_log_rpc/log_filter_service.h
@@ -58,10 +58,12 @@ class FilterService final
           (protobuf::SizeOfFieldEnum(
                log::FilterRule::Fields::LEVEL_GREATER_THAN_OR_EQUAL, 7) +
            protobuf::SizeOfFieldBytes(log::FilterRule::Fields::MODULE_EQUALS,
-                                      6) +
+                                      cfg::kMaxModuleNameBytes) +
            protobuf::SizeOfFieldUint32(log::FilterRule::Fields::ANY_FLAGS_SET,
                                        1) +
-           protobuf::SizeOfFieldEnum(log::FilterRule::Fields::ACTION, 2));
+           protobuf::SizeOfFieldEnum(log::FilterRule::Fields::ACTION, 2) +
+           protobuf::SizeOfFieldBytes(log::FilterRule::Fields::THREAD_EQUALS,
+                                      cfg::kMaxThreadNameBytes));
 
   static constexpr size_t kFilterIdsResponseBufferSize =
       kMinSupportedFilters *