diff --git a/src/game/boe.actions.cpp b/src/game/boe.actions.cpp
index 47ed2a9e..67036eb0 100644
--- a/src/game/boe.actions.cpp
+++ b/src/game/boe.actions.cpp
@@ -41,6 +41,7 @@
 #include "tools/enum_map.hpp"
 #include <string>
 #include <boost/lexical_cast.hpp>
+#include <sstream>
 
 rectangle item_screen_button_rects[9] = {
 	{125,10,141,28},{125,40,141,58},{125,68,141,86},{125,98,141,116},{125,126,141,144},{125,156,141,174},
@@ -108,6 +109,7 @@ extern sf::RenderWindow mini_map;
 extern std::shared_ptr<cScrollbar> text_sbar,item_sbar,shop_sbar;
 extern short shop_identify_cost, shop_recharge_amount;
 
+extern bool record_advance_time;
 
 const char *dir_string[] = {"North", "NorthEast", "East", "SouthEast", "South", "SouthWest", "West", "NorthWest"};
 char get_new_terrain();
@@ -1622,6 +1624,40 @@ bool handle_action(const sf::Event& event, cFramerateLimiter& fps_limiter) {
 }
 
 void advance_time(bool did_something, bool need_redraw, bool need_reprint) {
+	if(recording && record_advance_time){
+		std::map<std::string,std::string> info;
+		info["did_something"] = bool_to_str(did_something);
+		info["need_redraw"] = bool_to_str(need_redraw);
+		info["need_reprint"] = bool_to_str(need_reprint);
+		record_action("advance_time", info);
+	}
+	if(replaying && record_advance_time){
+		if(next_action_type() == "advance_time"){
+			Element& element = pop_next_action();
+			std::map<std::string,std::string> info = info_from_action(element);
+			std::ostringstream sstr;
+			sstr << std::boolalpha;
+			bool wrong_args = false;
+			if(did_something != str_to_bool(info["did_something"])){
+				wrong_args = true;
+				sstr << "did_something: expected " << !did_something << ", was " << did_something << ". ";
+			}
+			if(need_redraw != str_to_bool(info["need_redraw"])){
+				wrong_args = true;
+				sstr << "need_redraw: expected " << !need_redraw << ", was " << need_redraw << ". ";
+			}
+			if(need_reprint != str_to_bool(info["need_reprint"])){
+				wrong_args = true;
+				sstr << "need_reprint: expected " << !need_reprint << ", was " << need_reprint << ". ";
+			}
+			if(wrong_args){
+				throw std::string { "Replay system internal error! advance_time() was called with the wrong args. " } + sstr.str();
+			}
+		}else{
+			throw std::string { "Replay system internal error! advance_time() was called following an action which does not advance time: " } + last_action_type;
+		}
+	}
+
  	// MARK: At this point, see if any specials have been queued up, and deal with them
 	// Note: We just check once here instead of looping because run_special also pulls from the queue.
 	if(!special_queue.empty()) {
diff --git a/src/game/boe.main.cpp b/src/game/boe.main.cpp
index 7a2c8acf..f3ce48fa 100644
--- a/src/game/boe.main.cpp
+++ b/src/game/boe.main.cpp
@@ -234,6 +234,8 @@ static void init_ui() {
 	init_buttons();
 }
 
+bool record_advance_time = false;
+
 static void process_args(int argc, char* argv[]) {
 	preprocess_args(argc, argv);
 	clara::Args args(argc, argv);
@@ -243,6 +245,7 @@ static void process_args(int argc, char* argv[]) {
 	boost::optional<double> replay_speed;
 	cli |= clara::Opt(record_to, "record")["--record"]("Records a replay of your session to the specified XML file.");
 	cli |= clara::Opt(record_unique)["--unique"]("When recording, automatically insert a timestamp into the filename to guarantee uniqueness.");
+	cli |= clara::Opt(record_advance_time)["--advance-time"]("Record and validate advance_time() calls for internal testing of the replay system.");
 	cli |= clara::Opt(replay, "replay-file")["--replay"]("Replays a previously-recorded session from the specified XML file.");
 	cli |= clara::Opt(replay_speed, "fps")["--replay-speed"]("Specifies how quickly actions are processed while replaying");
 	cli |= clara::Arg(saved_game, "save-file")("Launch and load a saved game file.");
@@ -535,6 +538,12 @@ static void replay_next_action() {
 		handle_monster_info_menu(boost::lexical_cast<int>(next_action.GetText()));
 	}else if(t == "cancel_item_target"){
 		cancel_item_target();
+	}else if(t == "advance_time"){
+		if(record_advance_time){
+			throw std::string { "Replay system internal error! advance_time() was supposed to be called by the last action, but wasn't." };
+		}else{
+			throw std::string { "The action log you're replaying contains advance_time() recordings. The additional --advance-time flag is required to process it." };
+		}
 	}else{
 		std::ostringstream sstr;
 		sstr << "Couldn't replay action: " << next_action;
diff --git a/src/tools/replay.cpp b/src/tools/replay.cpp
index 83622a93..00dda3fe 100644
--- a/src/tools/replay.cpp
+++ b/src/tools/replay.cpp
@@ -25,6 +25,8 @@ using base64 = cppcodec::base64_rfc4648;
 bool recording = false;
 bool replaying = false;
 
+std::string last_action_type;
+
 using namespace ticpp;
 Document log_document;
 std::string log_file;
@@ -154,6 +156,8 @@ Element& pop_next_action(std::string expected_action_type) {
 		replay_fps_limit->frame_finished();
 	}
 	
+	last_action_type = to_return->Value();
+
 	return *to_return;
 }
 
diff --git a/src/tools/replay.hpp b/src/tools/replay.hpp
index b62ee7b8..269cd2a1 100644
--- a/src/tools/replay.hpp
+++ b/src/tools/replay.hpp
@@ -18,6 +18,8 @@ struct word_rect_t;
 extern bool recording;
 extern bool replaying;
 
+extern std::string last_action_type;
+
 extern bool init_action_log(std::string command, std::string file);
 extern void record_action(std::string action_type, std::string inner_text, bool cdata = false);
 extern void record_action(std::string action_type, std::map<std::string,std::string> info);