diff --git a/tests/conform/test-cogl-materials.c b/tests/conform/test-cogl-materials.c
index 04238aea6..d5a21ab2f 100644
--- a/tests/conform/test-cogl-materials.c
+++ b/tests/conform/test-cogl-materials.c
@@ -155,19 +155,27 @@ test_using_all_layers (TestState *state, int x, int y)
   /* FIXME: Cogl doesn't provide a way to query the maximum number of
      texture layers so for now we'll just ask GL directly. */
 #ifdef HAVE_COGL_GLES2
-  /* GLES 2 doesn't have GL_MAX_TEXTURE_UNITS and it uses
-     GL_MAX_TEXTURE_IMAGE_UNITS instead */
-  glGetIntegerv (GL_MAX_TEXTURE_IMAGE_UNITS, &n_layers);
-  /* Cogl can't support more than 16 layers under GLES 2 */
-  if (n_layers > 16)
-    n_layers = 16;
+  {
+    GLint n_image_units, n_attribs;
+    /* GLES 2 doesn't have GL_MAX_TEXTURE_UNITS and it uses
+       GL_MAX_TEXTURE_IMAGE_UNITS instead */
+    glGetIntegerv (GL_MAX_TEXTURE_IMAGE_UNITS, &n_image_units);
+    /* Cogl needs a vertex attrib for each layer to upload the texture
+       coordinates */
+    glGetIntegerv (GL_MAX_VERTEX_ATTRIBS, &n_attribs);
+    /* We can't use two of the attribs because they are used by the
+       position and color */
+    n_attribs -= 2;
+    n_layers = MIN (n_attribs, n_image_units);
+  }
 #else
   glGetIntegerv (GL_MAX_TEXTURE_UNITS, &n_layers);
+#endif
+  /* FIXME: is this still true? */
   /* Cogl currently can't cope with more than 32 layers so we'll also
      limit the maximum to that. */
   if (n_layers > 32)
     n_layers = 32;
-#endif
 
   for (i = 0; i < n_layers; i++)
     {