diff --git a/js-dos/README.md b/js-dos/README.md
index a62521eb0..4aeeaa802 100644
--- a/js-dos/README.md
+++ b/js-dos/README.md
@@ -3,4 +3,14 @@ js-dos
 
 The aim of the project is to provide nice web-API for em-dosbox.
 
-uztool - is a tool for extraction zip archives
\ No newline at end of file
+uztool - is a tool for extraction zip archives
+
+# How to build
+
+```
+cd js-dos
+mkdir build
+cd build
+./emcmake cmake ../api
+make -j4
+```
\ No newline at end of file
diff --git a/js-dos/api/CMakeLists.txt b/js-dos/api/CMakeLists.txt
index 74c057954..d0c82c0b6 100644
--- a/js-dos/api/CMakeLists.txt
+++ b/js-dos/api/CMakeLists.txt
@@ -3,7 +3,8 @@ cmake_minimum_required(VERSION 2.8)
 project(js-dos)
 
 set(CMAKE_BUILD_TYPE Release)
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-implicit-function-declaration")
+set(CMAKE_C_FLAGS_RELEASE "-O3 -DNDEBUG -Wno-implicit-function-declaration")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE}")
 set(ROOT "${CMAKE_CURRENT_SOURCE_DIR}/../..")
 
 if(EMSCRIPTEN)
diff --git a/src/dosbox.cpp b/src/dosbox.cpp
index 9972cc3f0..4025c1b4f 100644
--- a/src/dosbox.cpp
+++ b/src/dosbox.cpp
@@ -358,8 +358,9 @@ void DOSBOX_RunMachine(void){
 		 * Anything taking a long time will probably run indefinitely,
 		 * making DOSBox appear to hang.
 		 */
-		if (GetTicks() - ticksStart > 1000) {
+		if (GetTicks() - ticksStart > 10000) {
 			LOG_MSG("Emulation aborted due to nested emulation timeout.");
+			printf("Ticks passed %d\n", GetTicks() - ticksStart);
 			em_exit(1);
 			break;
 		}