diff --git a/include/gfx/gfx.h b/include/gfx/gfx.h
index 6a02801..e86299d 100644
--- a/include/gfx/gfx.h
+++ b/include/gfx/gfx.h
@@ -111,6 +111,7 @@ void gfx_fill(struct texture *dst, int x, int y, int w, int h, int r, int g, int
 void gfx_fill_alpha_color(struct texture *dst, int x, int y, int w, int h, int r, int g, int b, int a);
 void gfx_fill_amap(struct texture *dst, int x, int y, int w, int h, int a);
 void gfx_add_da_daxsa(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h);
+void gfx_sub_da_daxsa(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h);
 void gfx_copy_stretch(struct texture *dst, int dx, int dy, int dw, int dh, struct texture *src, int sx, int sy, int sw, int sh);
 void gfx_copy_stretch_amap(struct texture *dst, int dx, int dy, int dw, int dh, struct texture *src, int sx, int sy, int sw, int sh);
 void gfx_copy_rot_zoom(Texture *dst, Texture *src, int sx, int sy, int w, int h, float rotate, float mag);
diff --git a/src/draw.c b/src/draw.c
index 4ce3204..0761be1 100644
--- a/src/draw.c
+++ b/src/draw.c
@@ -345,6 +345,16 @@ void gfx_add_da_daxsa(Texture *dst, int dx, int dy, Texture *src, int sx, int sy
 	restore_blend_mode();
 }
 
+void gfx_sub_da_daxsa(struct texture *dst, int dx, int dy, struct texture *src, int sx, int sy, int w, int h)
+{
+	glBlendFuncSeparate(GL_ZERO, GL_ONE, GL_ONE_MINUS_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+	struct copy_data data = COPY_DATA(dx, dy, sx, sy, w, h);
+	run_copy_shader(&copy_shader.s, dst, src, &data);
+
+	restore_blend_mode();
+}
+
 // FIXME: DrawGraph.dll does some really strange clipping on the src/dst rectangles
 //        before drawing. This implementation does what you would normally expect
 //        a stretch function to do when passed negative (x,y) coordinates.
diff --git a/src/hll/DrawGraph.c b/src/hll/DrawGraph.c
index 2d62d16..fb92e67 100644
--- a/src/hll/DrawGraph.c
+++ b/src/hll/DrawGraph.c
@@ -102,6 +102,11 @@ static void DrawGraph_AddDA_DAxSA(int dst, int dx, int dy, int src, int sx, int
 	gfx_add_da_daxsa(DTEX(dst), dx, dy, STEX(src), sx, sy, w, h);
 }
 
+void DrawGraph_SubDA_DAxSA(int dst, int dx, int dy, int src, int sx, int sy, int w, int h)
+{
+	gfx_sub_da_daxsa(DTEX(dst), dx, dy, STEX(src), sx, sy, w, h);
+}
+
 static void DrawGraph_CopyStretch(int dst, int dx, int dy, int dw, int dh, int src, int sx, int sy, int sw, int sh)
 {
 	gfx_copy_stretch(DTEX(dst), dx, dy, dw, dh, STEX(src), sx, sy, sw, sh);
@@ -191,7 +196,6 @@ static void DrawGraph_SetFontName(struct string *text)
 //void DrawGraph_ScreenDA_DAxSA(int dst, int dx, int dy, int src, int sx, int sy, int w, int h);
 //void DrawGraph_SpriteCopyAMap(int dst, int dx, int dy, int src, int sx, int sy, int w, int h, int key);
 //void DrawGraph_BlendDA_DAxSA, int dst, int dx, int dy, int src, int sx, int sy, int w, int h);
-//void DrawGraph_SubDA_DAxSA, int dst, int dx, int dy, int src, int sx, int sy, int w, int h);
 //void DrawGraph_BrightDestOnly(int dst, int x, int y, int w, int h, int rate);
 //void DrawGraph_CopyTextureWrap(int dst, int dx, int dy, int dw, int dh, int src, int sx, int sy, int sw, int sh, int u, int v);
 //void DrawGraph_CopyTextureWrapAlpha(int dst, int dx, int dy, int dw, int dh, int src, int sx, int sy, int sw, int sh, int u, int v, int alpha);
@@ -261,7 +265,7 @@ HLL_LIBRARY(DrawGraph,
 	    HLL_EXPORT(AddDA_DAxSA, DrawGraph_AddDA_DAxSA),
 	    //HLL_EXPORT(SpriteCopyAMap, DrawGraph_SpriteCopyAMap),
 	    //HLL_EXPORT(BlendDA_DAxSA, DrawGraph_BlendDA_DAxSA),
-	    //HLL_EXPORT(SubDA_DAxSA, DrawGraph_SubDA_DAxSA),
+	    HLL_EXPORT(SubDA_DAxSA, DrawGraph_SubDA_DAxSA),
 	    //HLL_EXPORT(BrightDestOnly, DrawGraph_BrightDestOnly),
 	    //HLL_EXPORT(CopyTextureWrap, DrawGraph_CopyTextureWrap),
 	    //HLL_EXPORT(CopyTextureWrapAlpha, DrawGraph_CopyTextureWrapAlpha),