diff --git a/Makefile.emscripten b/Makefile.emscripten
index fb77ee3839..b1dd96469a 100644
--- a/Makefile.emscripten
+++ b/Makefile.emscripten
@@ -22,6 +22,7 @@
 #
 # FHEROES2_STRICT_COMPILATION: build in strict compilation mode (turns warnings into errors)
 # FHEROES2_WITH_DEBUG: build in debug mode
+# FHEROES2_WITH_MODULARIZE: wrap the emitted JS code in a function that returns a promise
 # FHEROES2_DATA: set the built-in path to the fheroes2 data directory (e.g. /usr/share/fheroes2)
 
 .PHONY: all clean translations
diff --git a/src/dist/Makefile.emscripten b/src/dist/Makefile.emscripten
index 8010a5fbab..c5aac50d11 100644
--- a/src/dist/Makefile.emscripten
+++ b/src/dist/Makefile.emscripten
@@ -43,3 +43,10 @@ ifdef FHEROES2_WITH_DEBUG
 CCFLAGS := $(CCFLAGS) -gsource-map
 LDFLAGS := $(LDFLAGS) -gsource-map
 endif
+
+ifdef FHEROES2_WITH_MODULARIZE
+LDFLAGS := $(LDFLAGS) \
+	-sMODULARIZE \
+	-sEXPORTED_RUNTIME_METHODS=FS,ENV,noExitRuntime,addOnExit,run \
+	-sEXPORT_NAME=fheroes2
+endif