diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index e94c637e4..41de5ddcf 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -712,13 +712,12 @@ static void HWR_RenderSkyPlane(extrasubsector_t *xsub, fixed_t fixedheight)
 
 #endif //doplanes
 
-FBITFIELD HWR_GetBlendModeFlag(INT32 ast)
+FBITFIELD HWR_GetBlendModeFlag(INT32 style)
 {
-	switch (ast)
+	switch (style)
 	{
-		case AST_COPY:
-		case AST_OVERLAY:
-			return PF_Masked;
+		case AST_TRANSLUCENT:
+			return PF_Translucent;
 		case AST_ADD:
 			return PF_Additive;
 		case AST_SUBTRACT:
@@ -728,10 +727,8 @@ FBITFIELD HWR_GetBlendModeFlag(INT32 ast)
 		case AST_MODULATE:
 			return PF_Multiplicative;
 		default:
-			return PF_Translucent;
+			return PF_Masked;
 	}
-
-	return 0;
 }
 
 UINT8 HWR_GetTranstableAlpha(INT32 transtablenum)
@@ -757,7 +754,7 @@ UINT8 HWR_GetTranstableAlpha(INT32 transtablenum)
 
 FBITFIELD HWR_SurfaceBlend(INT32 style, INT32 transtablenum, FSurfaceInfo *pSurf)
 {
-	if (!transtablenum || style == AST_COPY || style == AST_OVERLAY)
+	if (!transtablenum || style <= AST_COPY || style >= AST_OVERLAY)
 	{
 		pSurf->PolyColor.s.alpha = 0xff;
 		return PF_Masked;
diff --git a/src/hardware/hw_main.h b/src/hardware/hw_main.h
index 4ad09aa3d..2c7d237bf 100644
--- a/src/hardware/hw_main.h
+++ b/src/hardware/hw_main.h
@@ -69,7 +69,7 @@ void HWR_Lighting(FSurfaceInfo *Surface, INT32 light_level, extracolormap_t *col
 UINT8 HWR_FogBlockAlpha(INT32 light, extracolormap_t *colormap); // Let's see if this can work
 
 UINT8 HWR_GetTranstableAlpha(INT32 transtablenum);
-FBITFIELD HWR_GetBlendModeFlag(INT32 ast);
+FBITFIELD HWR_GetBlendModeFlag(INT32 style);
 FBITFIELD HWR_SurfaceBlend(INT32 style, INT32 transtablenum, FSurfaceInfo *pSurf);
 FBITFIELD HWR_TranstableToAlpha(INT32 transtablenum, FSurfaceInfo *pSurf);
 
diff --git a/src/lua_mobjlib.c b/src/lua_mobjlib.c
index 65adceb15..994f6a789 100644
--- a/src/lua_mobjlib.c
+++ b/src/lua_mobjlib.c
@@ -12,6 +12,7 @@
 
 #include "doomdef.h"
 #include "fastcmp.h"
+#include "r_data.h"
 #include "r_skins.h"
 #include "p_local.h"
 #include "g_game.h"
@@ -654,8 +655,13 @@ static int mobj_set(lua_State *L)
 		break;
 	}
 	case mobj_blendmode:
-		mo->blendmode = (INT32)luaL_checkinteger(L, 3);
+	{
+		INT32 blendmode = (INT32)luaL_checkinteger(L, 3);
+		if (blendmode < 0 || blendmode > AST_OVERLAY)
+			return luaL_error(L, "mobj.blendmode %d out of range (0 - %d).", blendmode, AST_OVERLAY);
+		mo->blendmode = blendmode;
 		break;
+	}
 	case mobj_bnext:
 		return NOSETPOS;
 	case mobj_bprev:
diff --git a/src/r_draw.c b/src/r_draw.c
index 9a835ee58..1d2d8352f 100644
--- a/src/r_draw.c
+++ b/src/r_draw.c
@@ -341,7 +341,7 @@ UINT8 *R_GetBlendTable(int style, INT32 alphalevel)
 {
 	size_t offs;
 
-	if (style == AST_COPY || style == AST_OVERLAY)
+	if (style <= AST_COPY || style >= AST_OVERLAY)
 		return NULL;
 
 	offs = (ClipBlendLevel(style, alphalevel) << FF_TRANSSHIFT);
@@ -371,7 +371,7 @@ UINT8 *R_GetBlendTable(int style, INT32 alphalevel)
 
 boolean R_BlendLevelVisible(INT32 blendmode, INT32 alphalevel)
 {
-	if (blendmode == AST_COPY || blendmode == AST_SUBTRACT || blendmode == AST_MODULATE || blendmode == AST_OVERLAY)
+	if (blendmode <= AST_COPY || blendmode == AST_SUBTRACT || blendmode == AST_MODULATE || blendmode >= AST_OVERLAY)
 		return true;
 
 	return (alphalevel < BlendTab_Count[BlendTab_FromStyle[blendmode]]);