diff --git a/Makefile.libretro b/Makefile.libretro
index cb72273..6753154 100644
--- a/Makefile.libretro
+++ b/Makefile.libretro
@@ -359,10 +359,13 @@ else ifneq (,$(findstring armv,$(platform)))
       ASFLAGS += -mfloat-abi=hard
    endif
    CFLAGS += -DARM
+
+# Emscripten
 else ifeq ($(platform), emscripten)
    TARGET := $(TARGET_NAME)_libretro_$(platform).bc
    STATIC_LINKING = 1
-   HAS_GPU=0
+   HAS_GPU = 1
+   GLES = 1
 
 # GCW0
 else ifeq ($(platform), gcw0)
@@ -689,8 +692,13 @@ else
       CFLAGS   += -MT
       CXXFLAGS += -MT
    endif
+   ifeq ($(platform), emscripten)
+      CFLAGS   += -O3 -DNDEBUG
+      CXXFLAGS += -O3 -DNDEBUG
+   else
       CFLAGS   += -O2 -DNDEBUG
       CXXFLAGS += -O2 -DNDEBUG
+   endif
 endif
 
 LDFLAGS += $(LIBM)