diff --git a/lib/drmtest.c b/lib/drmtest.c
index d035f5e7..abcbba95 100644
--- a/lib/drmtest.c
+++ b/lib/drmtest.c
@@ -1367,6 +1367,14 @@ void kmstest_paint_color(cairo_t *cr, int x, int y, int w, int h,
 	cairo_fill(cr);
 }
 
+void kmstest_paint_color_alpha(cairo_t *cr, int x, int y, int w, int h,
+			       double r, double g, double b, double a)
+{
+	cairo_rectangle(cr, x, y, w, h);
+	cairo_set_source_rgba(cr, r, g, b, a);
+	cairo_fill(cr);
+}
+
 void
 kmstest_paint_color_gradient(cairo_t *cr, int x, int y, int w, int h,
 		     int r, int g, int b)
diff --git a/lib/drmtest.h b/lib/drmtest.h
index 3a3900ef..609e7d84 100644
--- a/lib/drmtest.h
+++ b/lib/drmtest.h
@@ -363,6 +363,8 @@ void kmstest_remove_fb(int fd, struct kmstest_fb *fb_info);
 cairo_t *kmstest_get_cairo_ctx(int fd, struct kmstest_fb *fb);
 void kmstest_paint_color(cairo_t *cr, int x, int y, int w, int h,
 			 double r, double g, double b);
+void kmstest_paint_color_alpha(cairo_t *cr, int x, int y, int w, int h,
+			       double r, double g, double b, double a);
 void kmstest_paint_color_gradient(cairo_t *cr, int x, int y, int w, int h,
 				  int r, int g, int b);
 void kmstest_paint_test_pattern(cairo_t *cr, int width, int height);