diff --git a/src/common/fb_exception.cpp b/src/common/fb_exception.cpp
index 1461a343b5..a31b82ce1d 100644
--- a/src/common/fb_exception.cpp
+++ b/src/common/fb_exception.cpp
@@ -29,7 +29,7 @@ private:
 		FB_THREAD_ID thread;
 
 	public:
-		ThreadBuffer(FB_THREAD_ID thr) : buffer_ptr(buffer), thread(thr) { }
+		explicit ThreadBuffer(FB_THREAD_ID thr) : buffer_ptr(buffer), thread(thr) { }
 
 		const char* alloc(const char* string, size_t& length)
 		{
diff --git a/src/jrd/svc.cpp b/src/jrd/svc.cpp
index 9124572048..9528753687 100644
--- a/src/jrd/svc.cpp
+++ b/src/jrd/svc.cpp
@@ -129,7 +129,7 @@ namespace {
 	class ThreadIdHolder
 	{
 	public:
-		ThreadIdHolder(Jrd::Service::StatusStringsHelper& p) : strHelper(&p)
+		explicit ThreadIdHolder(Jrd::Service::StatusStringsHelper& p) : strHelper(&p)
 		{
 			MutexLockGuard guard(strHelper->mtx);
 			strHelper->workerThread = getThreadId();