diff --git a/src/emu/video/rgbgen.h b/src/emu/video/rgbgen.h
index 4359abb5780..83eba3035e6 100644
--- a/src/emu/video/rgbgen.h
+++ b/src/emu/video/rgbgen.h
@@ -374,7 +374,7 @@ INLINE void rgbaint_scale_channel_and_clamp(rgbaint *color, const rgbaint *color
     code provided by Michael Herf
 -------------------------------------------------*/
 
-INLINE rgb_t rgb_bilinear_filter(rgb_t rgb00, rgb_t rgb01, rgb_t rgb10, rgb_t rgb11, UINT8 u, UINT8 v)
+INLINE rgb_t rgb_bilinear_filter(UINT32 rgb00, UINT32 rgb01, UINT32 rgb10, UINT32 rgb11, UINT8 u, UINT8 v)
 {
 	UINT32 ag0, ag1, rb0, rb1;
 
@@ -396,7 +396,7 @@ INLINE rgb_t rgb_bilinear_filter(rgb_t rgb00, rgb_t rgb01, rgb_t rgb10, rgb_t rg
     code provided by Michael Herf
 -------------------------------------------------*/
 
-INLINE rgb_t rgba_bilinear_filter(rgb_t rgb00, rgb_t rgb01, rgb_t rgb10, rgb_t rgb11, UINT8 u, UINT8 v)
+INLINE rgb_t rgba_bilinear_filter(UINT32 rgb00, UINT32 rgb01, UINT32 rgb10, UINT32 rgb11, UINT8 u, UINT8 v)
 {
 	UINT32 ag0, ag1, rb0, rb1;
 
@@ -422,7 +422,7 @@ INLINE rgb_t rgba_bilinear_filter(rgb_t rgb00, rgb_t rgb01, rgb_t rgb10, rgb_t r
     code provided by Michael Herf
 -------------------------------------------------*/
 
-INLINE void rgbint_bilinear_filter(rgbint *color, rgb_t rgb00, rgb_t rgb01, rgb_t rgb10, rgb_t rgb11, UINT8 u, UINT8 v)
+INLINE void rgbint_bilinear_filter(rgbint *color, UINT32 rgb00, UINT32 rgb01, UINT32 rgb10, UINT32 rgb11, UINT8 u, UINT8 v)
 {
 	UINT32 ag0, ag1, rb0, rb1;
 
@@ -446,7 +446,7 @@ INLINE void rgbint_bilinear_filter(rgbint *color, rgb_t rgb00, rgb_t rgb01, rgb_
     code provided by Michael Herf
 -------------------------------------------------*/
 
-INLINE void rgbaint_bilinear_filter(rgbaint *color, rgb_t rgb00, rgb_t rgb01, rgb_t rgb10, rgb_t rgb11, UINT8 u, UINT8 v)
+INLINE void rgbaint_bilinear_filter(rgbaint *color, UINT32 rgb00, UINT32 rgb01, UINT32 rgb10, UINT32 rgb11, UINT8 u, UINT8 v)
 {
 	UINT32 ag0, ag1, rb0, rb1;