diff --git a/tests/files/grayscale_trns_8_should_be_grayscale_1.png b/tests/files/grayscale_trns_8_should_be_grayscale_1.png
new file mode 100644
index 00000000..a322aadb
Binary files /dev/null and b/tests/files/grayscale_trns_8_should_be_grayscale_1.png differ
diff --git a/tests/files/issue-426-01.png b/tests/files/issue-426-01.png
deleted file mode 100644
index 7349d388..00000000
Binary files a/tests/files/issue-426-01.png and /dev/null differ
diff --git a/tests/files/issue-426-02.png b/tests/files/issue-426-02.png
deleted file mode 100644
index e3031723..00000000
Binary files a/tests/files/issue-426-02.png and /dev/null differ
diff --git a/tests/reduction.rs b/tests/reduction.rs
index 17afb499..5e2755c7 100644
--- a/tests/reduction.rs
+++ b/tests/reduction.rs
@@ -938,6 +938,18 @@ fn grayscale_alpha_8_should_be_grayscale_trns_1() {
     );
 }
 
+#[test]
+fn grayscale_trns_8_should_be_grayscale_1() {
+    test_it_converts(
+        "tests/files/grayscale_trns_8_should_be_grayscale_1.png",
+        true,
+        GRAYSCALE,
+        BitDepth::Eight,
+        GRAYSCALE,
+        BitDepth::One,
+    );
+}
+
 #[test]
 fn small_files() {
     test_it_converts(
diff --git a/tests/regression.rs b/tests/regression.rs
index f5675ef4..822bce26 100644
--- a/tests/regression.rs
+++ b/tests/regression.rs
@@ -226,30 +226,6 @@ fn issue_182() {
     );
 }
 
-#[test]
-fn issue_426_01() {
-    test_it_converts(
-        "tests/files/issue-426-01.png",
-        None,
-        GRAYSCALE,
-        BitDepth::Eight,
-        GRAYSCALE,
-        BitDepth::One,
-    );
-}
-
-#[test]
-fn issue_426_02() {
-    test_it_converts(
-        "tests/files/issue-426-02.png",
-        None,
-        GRAYSCALE,
-        BitDepth::Eight,
-        GRAYSCALE,
-        BitDepth::One,
-    );
-}
-
 #[test]
 fn issue_553() {
     let png = test_it_converts(