diff --git a/test/buffer-diff.c b/test/buffer-diff.c
index 8fc3f891e..087ac459b 100644
--- a/test/buffer-diff.c
+++ b/test/buffer-diff.c
@@ -252,3 +252,11 @@ image_diff (const cairo_test_context_t *ctx,
 
     return CAIRO_STATUS_SUCCESS;
 }
+
+cairo_bool_t
+image_diff_is_failure (const buffer_diff_result_t *result,
+                       unsigned int                tolerance)
+{
+  return result->pixels_changed &&
+         result->max_diff > tolerance;
+}
diff --git a/test/buffer-diff.h b/test/buffer-diff.h
index c09bc6464..2cbb8959c 100644
--- a/test/buffer-diff.h
+++ b/test/buffer-diff.h
@@ -66,4 +66,8 @@ image_diff (const cairo_test_context_t *ctx,
 	    cairo_surface_t *surface_diff,
 	    buffer_diff_result_t *result);
 
+cairo_bool_t
+image_diff_is_failure (const buffer_diff_result_t *result,
+                       unsigned int                tolerance);
+
 #endif
diff --git a/test/cairo-test-trace.c b/test/cairo-test-trace.c
index ed81eb294..77ee84bc9 100644
--- a/test/cairo-test-trace.c
+++ b/test/cairo-test-trace.c
@@ -723,8 +723,7 @@ matches_reference (struct slave *slave)
 	    return FALSE;
 	}
 
-	if (slave->result.pixels_changed &&
-	    slave->result.max_diff > slave->target->error_tolerance) {
+	if (image_diff_is_failure (&slave->result, slave->target->error_tolerance)) {
 	    slave->difference = diff;
 	    return FALSE;
 	} else {
diff --git a/test/cairo-test.c b/test/cairo-test.c
index e2bc687b2..286df09ad 100644
--- a/test/cairo-test.c
+++ b/test/cairo-test.c
@@ -1319,8 +1319,7 @@ REPEAT:
 				  &result);
 	_xunlink (ctx, diff_png_path);
 	if (diff_status ||
-	    (result.pixels_changed &&
-	     result.max_diff > target->error_tolerance))
+            image_diff_is_failure (&result, target->error_tolerance))
 	{
 	    /* that failed, so check against the specific backend */
 	    ref_image = cairo_test_get_reference_image (ctx, ref_png_path,
@@ -1345,8 +1344,7 @@ REPEAT:
 				cairo_status_to_string (diff_status));
 		ret = CAIRO_TEST_FAILURE;
 	    }
-	    else if (result.pixels_changed &&
-		     result.max_diff > target->error_tolerance)
+	    else if (image_diff_is_failure (&result, target->error_tolerance))
 	    {
 		ret = CAIRO_TEST_FAILURE;
 
@@ -1403,8 +1401,7 @@ REPEAT:
 						  diff_image,
 						  &result);
 			if (diff_status == CAIRO_STATUS_SUCCESS &&
-			    (result.pixels_changed == 0 ||
-			     result.max_diff > target->error_tolerance))
+			    !image_diff_is_failure (&result, target->error_tolerance))
 			{
 			    ret = CAIRO_TEST_XFAILURE;
 			}
diff --git a/test/fallback-resolution.c b/test/fallback-resolution.c
index 1ffacb1b2..5b18a7efb 100644
--- a/test/fallback-resolution.c
+++ b/test/fallback-resolution.c
@@ -234,8 +234,7 @@ check_result (cairo_test_context_t *ctx,
 	cairo_test_log (ctx, "Error: Failed to compare images: %s\n",
 			cairo_status_to_string (status));
 	ret = FALSE;
-    } else if (result.pixels_changed &&
-	       result.max_diff > target->error_tolerance)
+    } else if (image_diff_is_failure (&result, target->error_tolerance))
     {
 	ret = FALSE;
 
diff --git a/test/xlib-surface.c b/test/xlib-surface.c
index a7ff02085..be44b148b 100644
--- a/test/xlib-surface.c
+++ b/test/xlib-surface.c
@@ -250,9 +250,9 @@ do_test (const cairo_test_context_t *ctx,
 		    use_pixmap ?
 		    "           " :
 		    (offscreen ? ", offscreen" : ",  onscreen"),
-		    result.pixels_changed ? "FAIL" : "PASS");
+		    image_diff_is_failure (&result, 0) ? "FAIL" : "PASS");
 
-    if (result.pixels_changed)
+    if (image_diff_is_failure (&result, 0))
 	return CAIRO_TEST_FAILURE;
     else
 	return CAIRO_TEST_SUCCESS;