diff --git a/src/jrd/trace/TraceCmdLine.cpp b/src/jrd/trace/TraceCmdLine.cpp
index b5fee6282ee..baaa7d253ff 100644
--- a/src/jrd/trace/TraceCmdLine.cpp
+++ b/src/jrd/trace/TraceCmdLine.cpp
@@ -210,6 +210,9 @@ void fbtrace(UtilSvc* uSvc, TraceSvcIntf* traceSvc)
 				case IN_SW_TRACE_LIST:
 					usage(uSvc, isc_trace_param_act_notcompat, sw->in_sw_name, action_sw->in_sw_name);
 					break;
+				default:
+					fb_assert(false);
+					break;
 			}
 
 			if (!session.ses_config.empty())
@@ -231,6 +234,9 @@ void fbtrace(UtilSvc* uSvc, TraceSvcIntf* traceSvc)
 				case IN_SW_TRACE_LIST:
 					usage(uSvc, isc_trace_param_act_notcompat, sw->in_sw_name, action_sw->in_sw_name);
 					break;
+				default:
+					fb_assert(false);
+					break;
 			}
 
 			if (!session.ses_name.empty())
@@ -250,6 +256,9 @@ void fbtrace(UtilSvc* uSvc, TraceSvcIntf* traceSvc)
 				case IN_SW_TRACE_LIST:
 					usage(uSvc, isc_trace_param_act_notcompat, sw->in_sw_name, action_sw->in_sw_name);
 					break;
+				default:
+					fb_assert(false);
+					break;
 			}
 
 			if (session.ses_id)
@@ -275,6 +284,9 @@ void fbtrace(UtilSvc* uSvc, TraceSvcIntf* traceSvc)
 				case IN_SW_TRACE_LIST:
 					usage(uSvc, isc_trace_param_act_notcompat, sw->in_sw_name, action_sw->in_sw_name);
 					break;
+				default:
+					fb_assert(false);
+					break;
 			}
 
 			if (!session.ses_plugins.empty())
@@ -374,6 +386,8 @@ void fbtrace(UtilSvc* uSvc, TraceSvcIntf* traceSvc)
 						(Arg::Gds(isc_io_error) << Arg::Str("read") << Arg::Str(fileName) <<
 							Arg::Gds(isc_io_read_err) << Arg::OsError()).raise();
 						break;
+					default:
+						fb_assert(false);
 				}
 			}
 			else
@@ -420,6 +434,8 @@ void fbtrace(UtilSvc* uSvc, TraceSvcIntf* traceSvc)
 			case IN_SW_TRACE_RESUME:
 				usage(uSvc, isc_trace_switch_param_miss, "ID", action_sw->in_sw_name);
 				break;
+			default:
+				fb_assert(false);
 		}
 	}
 
diff --git a/src/jrd/trace/TraceConfigStorage.cpp b/src/jrd/trace/TraceConfigStorage.cpp
index 67ea28fee70..f349182781c 100644
--- a/src/jrd/trace/TraceConfigStorage.cpp
+++ b/src/jrd/trace/TraceConfigStorage.cpp
@@ -178,7 +178,8 @@ void ConfigStorage::shutdown()
 void ConfigStorage::mutexBug(int state, const char* string)
 {
 	TEXT msg[BUFFER_TINY];
-	snprintf(msg, sizeof(msg), "ConfigStorage: mutex %s error, status = %d", string, state);
+	[[maybe_unused]] const int len = snprintf(msg, sizeof(msg), "ConfigStorage: mutex %s error, status = %d", string, state);
+	fb_assert(len >= 0 && static_cast<size_t>(len) < sizeof(msg));
 	fb_utils::logAndDie(msg);
 }
 
@@ -243,11 +244,13 @@ void ConfigStorage::checkAudit()
 
 		TraceSession session(*getDefaultMemoryPool());
 
-		fseek(cfgFile, 0, SEEK_END);
+		[[maybe_unused]] const int resultEnd = fseek(cfgFile, 0, SEEK_END);
+		fb_assert(resultEnd == 0);
 		const long len = ftell(cfgFile);
 		if (len)
 		{
-			fseek(cfgFile, 0, SEEK_SET);
+			[[maybe_unused]] const int resultSet = fseek(cfgFile, 0, SEEK_SET);
+			fb_assert(resultSet == 0);
 			char* p = session.ses_config.getBuffer(len + 1);
 
 			if (fread(p, 1, len, cfgFile) != size_t(len)) {
@@ -716,7 +719,7 @@ void ConfigStorage::addSession(TraceSession& session)
 	session.ses_flags |= trs_active;
 	slot->ses_flags = session.ses_flags;
 	time(&session.ses_start);
-
+	fb_assert(session.ses_start != (time_t) -1);
 	char* p = reinterpret_cast<char*> (header) + slot->offset;
 	Writer writer(p, slot->size);
 
diff --git a/src/jrd/trace/TraceLog.cpp b/src/jrd/trace/TraceLog.cpp
index ad024044f39..686a335ed70 100644
--- a/src/jrd/trace/TraceLog.cpp
+++ b/src/jrd/trace/TraceLog.cpp
@@ -299,7 +299,8 @@ void TraceLog::setFullMsg(const char* str)
 void TraceLog::mutexBug(int state, const char* string)
 {
 	TEXT msg[BUFFER_TINY];
-	snprintf(msg, sizeof(msg), "TraceLog: mutex %s error, status = %d", string, state);
+	[[maybe_unused]] const int len = snprintf(msg, sizeof(msg), "TraceLog: mutex %s error, status = %d", string, state);
+	fb_assert(len >= 0 && static_cast<size_t>(len) < sizeof(msg));
 	fb_utils::logAndDie(msg);
 }