diff --git a/glamor/glamor_trapezoid.c b/glamor/glamor_trapezoid.c
index fd63062f6..7813d825d 100644
--- a/glamor/glamor_trapezoid.c
+++ b/glamor/glamor_trapezoid.c
@@ -1068,8 +1068,6 @@ glamor_init_trapezoid_shader(ScreenPtr screen)
 	    "varying float trap_right_vertical_f;  \n"
 	    "float x_per_pix = 1.0;"
 	    "float y_per_pix = 1.0;"
-	    "bool trap_left_vertical = (abs(trap_left_vertical_f - 1.0) <= 0.0001);\n"
-	    "bool trap_right_vertical = (abs(trap_right_vertical_f - 1.0) <= 0.0001);\n"
 	    "\n"
 	    "float get_alpha_val() \n"
 	    "{  \n"
@@ -1077,6 +1075,16 @@ glamor_init_trapezoid_shader(ScreenPtr screen)
 	    "    float x_bottom_cut_left;  \n"
 	    "    float x_up_cut_right;  \n"
 	    "    float x_bottom_cut_right;  \n"
+	    "    bool trap_left_vertical;\n"
+	    "    bool trap_right_vertical;\n"
+	    "	 if (abs(trap_left_vertical_f - 1.0) <= 0.0001)\n"
+	    "		trap_left_vertical = true;\n"
+	    "	 else\n"
+	    "		trap_left_vertical = false;\n"
+	    "	 if (abs(trap_right_vertical_f - 1.0) <= 0.0001)\n"
+	    "		trap_right_vertical = true;\n"
+	    "	 else\n"
+	    "		trap_right_vertical = false;\n"
 	    "    \n"
 	    "    if(trap_left_vertical == true) {  \n"
 	    "        x_up_cut_left = trap_left_x;  \n"