diff --git a/cogl/test-fixtures/test-utils.c b/cogl/test-fixtures/test-utils.c
index 6834f9fac..47586867e 100644
--- a/cogl/test-fixtures/test-utils.c
+++ b/cogl/test-fixtures/test-utils.c
@@ -250,7 +250,17 @@ void
 test_utils_check_pixel_rgb (CoglFramebuffer *test_fb,
                             int x, int y, int r, int g, int b)
 {
-  test_utils_check_pixel (test_fb, x, y, (r << 24) | (g << 16) | (b << 8));
+  g_return_if_fail (r >= 0);
+  g_return_if_fail (g >= 0);
+  g_return_if_fail (b >= 0);
+  g_return_if_fail (r <= 0xFF);
+  g_return_if_fail (g <= 0xFF);
+  g_return_if_fail (b <= 0xFF);
+
+  test_utils_check_pixel (test_fb, x, y,
+                          (((guint32) r) << 24) |
+                          (((guint32) g) << 16) |
+                          (((guint32) b) << 8));
 }
 
 void
diff --git a/cogl/tests/conform/test-atlas-migration.c b/cogl/tests/conform/test-atlas-migration.c
index b5d04c3d3..877fb37d6 100644
--- a/cogl/tests/conform/test-atlas-migration.c
+++ b/cogl/tests/conform/test-atlas-migration.c
@@ -99,9 +99,9 @@ verify_texture (CoglTexture *texture, int size)
             };
 
           test_utils_compare_pixel (p,
-                                    (real_color.red << 24) |
-                                    (real_color.green << 16) |
-                                    (real_color.blue << 8) |
+                                    (((guint32) real_color.red) << 24) |
+                                    (((guint32) real_color.green) << 16) |
+                                    (((guint32) real_color.blue) << 8) |
                                     opacity);
           g_assert_cmpint (p[3], ==, opacity);