diff --git a/src/openttd.cpp b/src/openttd.cpp
index 0ec662e14a..efa36b0716 100644
--- a/src/openttd.cpp
+++ b/src/openttd.cpp
@@ -227,13 +227,19 @@ void CDECL assert_msg_error(int line, const char *file, const char *expr, const
 	vseprintf(b, lastof(buf), str, va);
 	va_end(va);
 
-	if (VideoDriver::GetInstance() == nullptr || VideoDriver::GetInstance()->HasGUI()) {
-		ShowOSErrorBox(buf, true);
-	}
+	fatalerror_common(buf);
+}
 
-	/* Set the error message for the crash log and then invoke it. */
-	CrashLog::SetErrorMessage(buf);
-	DoOSAbort();
+void assert_str_error(int line, const char *file, const char *expr, const char *str)
+{
+	char buf[2048];
+	seprintf(buf, lastof(buf), "Assertion failed at line %i of %s: %s\n%s", line, file, expr, str);
+	fatalerror_common(buf);
+}
+
+void assert_str_error(int line, const char *file, const char *expr, const std::string &str)
+{
+	assert_str_error(line, file, expr, str.c_str());
 }
 
 const char *assert_tile_info(uint32_t tile) {
diff --git a/src/stdafx.h b/src/stdafx.h
index 2bf48e5330..5104c34108 100644
--- a/src/stdafx.h
+++ b/src/stdafx.h
@@ -433,6 +433,8 @@ typedef uint64_t unaligned_uint64;
 void NORETURN CDECL usererror(const char *str, ...) WARN_FORMAT(1, 2);
 void NORETURN CDECL error(const char *str, ...) WARN_FORMAT(1, 2);
 void NORETURN CDECL assert_msg_error(int line, const char *file, const char *expr, const char *extra, const char *str, ...) WARN_FORMAT(5, 6);
+void NORETURN assert_str_error(int line, const char *file, const char *expr, const char *str);
+void NORETURN assert_str_error(int line, const char *file, const char *expr, const std::string &str);
 const char *assert_tile_info(uint32_t tile);
 #define NOT_REACHED() error("NOT_REACHED triggered at line %i of %s", __LINE__, __FILE__)
 
@@ -443,12 +445,14 @@ const char *assert_tile_info(uint32_t tile);
 #	define assert_msg(expression, ...) if (unlikely(!(expression))) assert_msg_error(__LINE__, __FILE__, #expression, nullptr, __VA_ARGS__);
 #	define assert_msg_tile(expression, tile, ...) if (unlikely(!(expression))) assert_msg_error(__LINE__, __FILE__, #expression, assert_tile_info(tile), __VA_ARGS__);
 #	define assert_tile(expression, tile) if (unlikely(!(expression))) error("Assertion failed at line %i of %s: %s\n\t%s", __LINE__, __FILE__, #expression, assert_tile_info(tile));
+#	define assert_str(expression, str) if (unlikely(!(expression))) assert_str_error(__LINE__, __FILE__, #expression, str);
 #else
 #	undef assert
 #	define assert(expression)
 #	define assert_msg(expression, ...)
 #	define assert_msg_tile(expression, tile, ...)
 #	define assert_tile(expression, tile)
+#	define assert_str(expression, str)
 #endif
 #if (!defined(NDEBUG) || defined(WITH_ASSERT)) && !defined(FEWER_ASSERTS)
 #	define WITH_FULL_ASSERTS