diff --git a/src/CommandOutput.h b/src/CommandOutput.h
index 3763d625f..81d9ddb84 100644
--- a/src/CommandOutput.h
+++ b/src/CommandOutput.h
@@ -17,7 +17,7 @@ public:
 	virtual ~cCommandOutputCallback() {};  // Force a virtual destructor in subclasses
 	
 	/// Syntax sugar function, calls Out() with Printf()-ed parameters; appends a "\n"
-	void Out(const char * a_Fmt, ...);
+	void Out(const char * a_Fmt, ...) FORMATSTRING(2,3);
 	
 	/// Called when the command wants to output anything; may be called multiple times
 	virtual void Out(const AString & a_Text) = 0;
diff --git a/src/Log.cpp b/src/Log.cpp
index 1ea327d5d..54e2b7812 100644
--- a/src/Log.cpp
+++ b/src/Log.cpp
@@ -118,7 +118,7 @@ void cLog::Log(const char * a_Format, va_list argList)
 
 	AString Line;
 	#ifdef _DEBUG
-	Printf(Line, "[%04x|%02d:%02d:%02d] %s", cIsThread::GetCurrentID(), timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec, Message.c_str());
+	Printf(Line, "[%04zu|%02d:%02d:%02d] %s", cIsThread::GetCurrentID(), timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec, Message.c_str());
 	#else
 	Printf(Line, "[%02d:%02d:%02d] %s", timeinfo->tm_hour, timeinfo->tm_min, timeinfo->tm_sec, Message.c_str());
 	#endif
diff --git a/src/Log.h b/src/Log.h
index cba248dae..340fa23bc 100644
--- a/src/Log.h
+++ b/src/Log.h
@@ -14,8 +14,8 @@ private:
 public:
 	cLog(const AString & a_FileName);
 	~cLog();
-	void Log(const char * a_Format, va_list argList);
-	void Log(const char * a_Format, ...);
+	void Log(const char * a_Format, va_list argList) FORMATSTRING(2,0);
+	void Log(const char * a_Format, ...) FORMATSTRING(2,3);
 	// tolua_begin
 	void SimpleLog(const char * a_String);
 	void OpenLog(const char * a_FileName);