diff --git a/tests/by-util/test_cksum.rs b/tests/by-util/test_cksum.rs
index a331f5b80..e94303a75 100644
--- a/tests/by-util/test_cksum.rs
+++ b/tests/by-util/test_cksum.rs
@@ -433,6 +433,146 @@ fn test_check_untagged_sha2_multiple_files() {
     }
 }
 
+#[test]
+fn test_sha3_wrong_length() {
+    for l in [0, 13, 819_111_123] {
+        new_ucmd!()
+            .arg("--algorithm=sha3")
+            .arg(format!("--length={l}"))
+            .arg("lorem_ipsum.txt")
+            .fails_with_code(1)
+            .no_stdout()
+            .stderr_contains(format!("invalid length: '{l}'"));
+    }
+}
+
+#[test]
+fn test_sha3_single_file() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--algorithm=sha3")
+            .arg(format!("--length={l}"))
+            .arg("lorem_ipsum.txt")
+            .succeeds()
+            .stdout_is_fixture(format!("sha3_{l}_single_file.expected"));
+    }
+}
+
+#[test]
+fn test_sha3_multiple_files() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--algorithm=sha3")
+            .arg(format!("--length={l}"))
+            .arg("lorem_ipsum.txt")
+            .arg("alice_in_wonderland.txt")
+            .succeeds()
+            .stdout_is_fixture(format!("sha3_{l}_multiple_files.expected"));
+    }
+}
+
+#[test]
+fn test_sha3_stdin() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--algorithm=sha3")
+            .arg(format!("--length={l}"))
+            .pipe_in_fixture("lorem_ipsum.txt")
+            .succeeds()
+            .stdout_is_fixture(format!("sha3_{l}_stdin.expected"));
+    }
+}
+
+#[test]
+fn test_untagged_sha3_single_file() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--untagged")
+            .arg("--algorithm=sha3")
+            .arg(format!("--length={l}"))
+            .arg("lorem_ipsum.txt")
+            .succeeds()
+            .stdout_is_fixture(format!("untagged/sha3_{l}_single_file.expected"));
+    }
+}
+
+#[test]
+fn test_untagged_sha3_multiple_files() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--untagged")
+            .arg("--algorithm=sha3")
+            .arg(format!("--length={l}"))
+            .arg("lorem_ipsum.txt")
+            .arg("alice_in_wonderland.txt")
+            .succeeds()
+            .stdout_is_fixture(format!("untagged/sha3_{l}_multiple_files.expected"));
+    }
+}
+
+#[test]
+fn test_untagged_sha3_stdin() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--untagged")
+            .arg("--algorithm=sha3")
+            .arg(format!("--length={l}"))
+            .pipe_in_fixture("lorem_ipsum.txt")
+            .succeeds()
+            .stdout_is_fixture(format!("untagged/sha3_{l}_stdin.expected"));
+    }
+}
+
+#[test]
+fn test_check_tagged_sha3_single_file() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--check")
+            .arg(format!("sha3_{l}_single_file.expected"))
+            .succeeds()
+            .stdout_is("lorem_ipsum.txt: OK\n");
+    }
+}
+
+#[test]
+fn test_check_tagged_sha3_multiple_files() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--check")
+            .arg(format!("sha3_{l}_multiple_files.expected"))
+            .succeeds()
+            .stdout_contains("lorem_ipsum.txt: OK\n")
+            .stdout_contains("alice_in_wonderland.txt: OK\n");
+    }
+}
+
+// When checking sha3 in untagged mode, the length is automatically deduced
+// from the length of the digest.
+#[test]
+fn test_check_untagged_sha3_single_file() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--check")
+            .arg("--algorithm=sha3")
+            .arg(format!("untagged/sha3_{l}_single_file.expected"))
+            .succeeds()
+            .stdout_is("lorem_ipsum.txt: OK\n");
+    }
+}
+
+#[test]
+fn test_check_untagged_sha3_multiple_files() {
+    for l in SHA_LENGTHS {
+        new_ucmd!()
+            .arg("--check")
+            .arg("--algorithm=sha3")
+            .arg(format!("untagged/sha3_{l}_multiple_files.expected"))
+            .succeeds()
+            .stdout_contains("lorem_ipsum.txt: OK\n")
+            .stdout_contains("alice_in_wonderland.txt: OK\n");
+    }
+}
+
 #[test]
 fn test_check_algo() {
     for algo in ["bsd", "sysv", "crc", "crc32b"] {
diff --git a/tests/fixtures/cksum/sha3_224_multiple_files.expected b/tests/fixtures/cksum/sha3_224_multiple_files.expected
new file mode 100644
index 000000000..f5671f684
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_224_multiple_files.expected
@@ -0,0 +1,2 @@
+SHA3-224 (lorem_ipsum.txt) = 00cf719da146d5f51f8969cb518aa2cb89dae71e0aad979b30398f13
+SHA3-224 (alice_in_wonderland.txt) = 33882bd6f47b47648950b4d6c606240c257eeae73e67b96610fd092c
diff --git a/tests/fixtures/cksum/sha3_224_single_file.expected b/tests/fixtures/cksum/sha3_224_single_file.expected
new file mode 100644
index 000000000..1944f173c
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_224_single_file.expected
@@ -0,0 +1 @@
+SHA3-224 (lorem_ipsum.txt) = 00cf719da146d5f51f8969cb518aa2cb89dae71e0aad979b30398f13
diff --git a/tests/fixtures/cksum/sha3_224_stdin.expected b/tests/fixtures/cksum/sha3_224_stdin.expected
new file mode 100644
index 000000000..a0f844909
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_224_stdin.expected
@@ -0,0 +1 @@
+SHA3-224 (-) = 00cf719da146d5f51f8969cb518aa2cb89dae71e0aad979b30398f13
diff --git a/tests/fixtures/cksum/sha3_256_multiple_files.expected b/tests/fixtures/cksum/sha3_256_multiple_files.expected
new file mode 100644
index 000000000..1e488167e
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_256_multiple_files.expected
@@ -0,0 +1,2 @@
+SHA3-256 (lorem_ipsum.txt) = c9b081db1c20bdb4d8f376f45b3fb412b48c75932451d13dd79bea61e7bddbe4
+SHA3-256 (alice_in_wonderland.txt) = 507e920028b617afd342fdd0da3096237d34e33e2490c38a743bf628124803ce
diff --git a/tests/fixtures/cksum/sha3_256_single_file.expected b/tests/fixtures/cksum/sha3_256_single_file.expected
new file mode 100644
index 000000000..86ac8a85b
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_256_single_file.expected
@@ -0,0 +1 @@
+SHA3-256 (lorem_ipsum.txt) = c9b081db1c20bdb4d8f376f45b3fb412b48c75932451d13dd79bea61e7bddbe4
diff --git a/tests/fixtures/cksum/sha3_256_stdin.expected b/tests/fixtures/cksum/sha3_256_stdin.expected
new file mode 100644
index 000000000..985f93225
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_256_stdin.expected
@@ -0,0 +1 @@
+SHA3-256 (-) = c9b081db1c20bdb4d8f376f45b3fb412b48c75932451d13dd79bea61e7bddbe4
diff --git a/tests/fixtures/cksum/sha3_384_multiple_files.expected b/tests/fixtures/cksum/sha3_384_multiple_files.expected
new file mode 100644
index 000000000..5d04e8dee
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_384_multiple_files.expected
@@ -0,0 +1,2 @@
+SHA3-384 (lorem_ipsum.txt) = 12e0dc8c08c0f84c5facbe95ece4e0b568b3b9fbe7dbd1a6751a118c2997aa70a78123cb3d6858dc31d353fc6b874bbe
+SHA3-384 (alice_in_wonderland.txt) = d999e51e60b98da41060c287f71592517554addc14b9d27cac3935b8b312fb1e3ffad2730a9cfe855cf0fdcbce6990c6
diff --git a/tests/fixtures/cksum/sha3_384_single_file.expected b/tests/fixtures/cksum/sha3_384_single_file.expected
new file mode 100644
index 000000000..16d9eb047
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_384_single_file.expected
@@ -0,0 +1 @@
+SHA3-384 (lorem_ipsum.txt) = 12e0dc8c08c0f84c5facbe95ece4e0b568b3b9fbe7dbd1a6751a118c2997aa70a78123cb3d6858dc31d353fc6b874bbe
diff --git a/tests/fixtures/cksum/sha3_384_stdin.expected b/tests/fixtures/cksum/sha3_384_stdin.expected
new file mode 100644
index 000000000..e96139e3e
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_384_stdin.expected
@@ -0,0 +1 @@
+SHA3-384 (-) = 12e0dc8c08c0f84c5facbe95ece4e0b568b3b9fbe7dbd1a6751a118c2997aa70a78123cb3d6858dc31d353fc6b874bbe
diff --git a/tests/fixtures/cksum/sha3_512_multiple_files.expected b/tests/fixtures/cksum/sha3_512_multiple_files.expected
new file mode 100644
index 000000000..adb0a71e8
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_512_multiple_files.expected
@@ -0,0 +1,2 @@
+SHA3-512 (lorem_ipsum.txt) = 77f7bb7e1827d7735dd1fd8bc4f4fa3ae1168a1529118c74b18f9abe69a8aecfb60fff0ecec17d2860af90e257e4fbd90048978c47fdda94f56b2ffa1d06448f
+SHA3-512 (alice_in_wonderland.txt) = 029486dea9b2bc8a2c90d852982c3a5297e626ed31a956443c6cc4794874bf4fdca76006bacc407bc101c09f85ecb3cea468c17bdfe3ad0ccff03edd786e07a8
diff --git a/tests/fixtures/cksum/sha3_512_single_file.expected b/tests/fixtures/cksum/sha3_512_single_file.expected
new file mode 100644
index 000000000..b1af502b1
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_512_single_file.expected
@@ -0,0 +1 @@
+SHA3-512 (lorem_ipsum.txt) = 77f7bb7e1827d7735dd1fd8bc4f4fa3ae1168a1529118c74b18f9abe69a8aecfb60fff0ecec17d2860af90e257e4fbd90048978c47fdda94f56b2ffa1d06448f
diff --git a/tests/fixtures/cksum/sha3_512_stdin.expected b/tests/fixtures/cksum/sha3_512_stdin.expected
new file mode 100644
index 000000000..9cb103cfe
--- /dev/null
+++ b/tests/fixtures/cksum/sha3_512_stdin.expected
@@ -0,0 +1 @@
+SHA3-512 (-) = 77f7bb7e1827d7735dd1fd8bc4f4fa3ae1168a1529118c74b18f9abe69a8aecfb60fff0ecec17d2860af90e257e4fbd90048978c47fdda94f56b2ffa1d06448f
diff --git a/tests/fixtures/cksum/untagged/sha3_224_multiple_files.expected b/tests/fixtures/cksum/untagged/sha3_224_multiple_files.expected
new file mode 100644
index 000000000..282be42ab
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_224_multiple_files.expected
@@ -0,0 +1,2 @@
+00cf719da146d5f51f8969cb518aa2cb89dae71e0aad979b30398f13  lorem_ipsum.txt
+33882bd6f47b47648950b4d6c606240c257eeae73e67b96610fd092c  alice_in_wonderland.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_224_single_file.expected b/tests/fixtures/cksum/untagged/sha3_224_single_file.expected
new file mode 100644
index 000000000..17c109ce4
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_224_single_file.expected
@@ -0,0 +1 @@
+00cf719da146d5f51f8969cb518aa2cb89dae71e0aad979b30398f13  lorem_ipsum.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_224_stdin.expected b/tests/fixtures/cksum/untagged/sha3_224_stdin.expected
new file mode 100644
index 000000000..4dfe480ec
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_224_stdin.expected
@@ -0,0 +1 @@
+00cf719da146d5f51f8969cb518aa2cb89dae71e0aad979b30398f13  -
diff --git a/tests/fixtures/cksum/untagged/sha3_256_multiple_files.expected b/tests/fixtures/cksum/untagged/sha3_256_multiple_files.expected
new file mode 100644
index 000000000..2c33a9b2c
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_256_multiple_files.expected
@@ -0,0 +1,2 @@
+c9b081db1c20bdb4d8f376f45b3fb412b48c75932451d13dd79bea61e7bddbe4  lorem_ipsum.txt
+507e920028b617afd342fdd0da3096237d34e33e2490c38a743bf628124803ce  alice_in_wonderland.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_256_single_file.expected b/tests/fixtures/cksum/untagged/sha3_256_single_file.expected
new file mode 100644
index 000000000..5e250eb9b
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_256_single_file.expected
@@ -0,0 +1 @@
+c9b081db1c20bdb4d8f376f45b3fb412b48c75932451d13dd79bea61e7bddbe4  lorem_ipsum.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_256_stdin.expected b/tests/fixtures/cksum/untagged/sha3_256_stdin.expected
new file mode 100644
index 000000000..3d612bf21
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_256_stdin.expected
@@ -0,0 +1 @@
+c9b081db1c20bdb4d8f376f45b3fb412b48c75932451d13dd79bea61e7bddbe4  -
diff --git a/tests/fixtures/cksum/untagged/sha3_384_multiple_files.expected b/tests/fixtures/cksum/untagged/sha3_384_multiple_files.expected
new file mode 100644
index 000000000..91ee0cfa8
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_384_multiple_files.expected
@@ -0,0 +1,2 @@
+12e0dc8c08c0f84c5facbe95ece4e0b568b3b9fbe7dbd1a6751a118c2997aa70a78123cb3d6858dc31d353fc6b874bbe  lorem_ipsum.txt
+d999e51e60b98da41060c287f71592517554addc14b9d27cac3935b8b312fb1e3ffad2730a9cfe855cf0fdcbce6990c6  alice_in_wonderland.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_384_single_file.expected b/tests/fixtures/cksum/untagged/sha3_384_single_file.expected
new file mode 100644
index 000000000..ae620394d
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_384_single_file.expected
@@ -0,0 +1 @@
+12e0dc8c08c0f84c5facbe95ece4e0b568b3b9fbe7dbd1a6751a118c2997aa70a78123cb3d6858dc31d353fc6b874bbe  lorem_ipsum.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_384_stdin.expected b/tests/fixtures/cksum/untagged/sha3_384_stdin.expected
new file mode 100644
index 000000000..9f5f7ca07
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_384_stdin.expected
@@ -0,0 +1 @@
+12e0dc8c08c0f84c5facbe95ece4e0b568b3b9fbe7dbd1a6751a118c2997aa70a78123cb3d6858dc31d353fc6b874bbe  -
diff --git a/tests/fixtures/cksum/untagged/sha3_512_multiple_files.expected b/tests/fixtures/cksum/untagged/sha3_512_multiple_files.expected
new file mode 100644
index 000000000..33121a5fd
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_512_multiple_files.expected
@@ -0,0 +1,2 @@
+77f7bb7e1827d7735dd1fd8bc4f4fa3ae1168a1529118c74b18f9abe69a8aecfb60fff0ecec17d2860af90e257e4fbd90048978c47fdda94f56b2ffa1d06448f  lorem_ipsum.txt
+029486dea9b2bc8a2c90d852982c3a5297e626ed31a956443c6cc4794874bf4fdca76006bacc407bc101c09f85ecb3cea468c17bdfe3ad0ccff03edd786e07a8  alice_in_wonderland.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_512_single_file.expected b/tests/fixtures/cksum/untagged/sha3_512_single_file.expected
new file mode 100644
index 000000000..edece7f36
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_512_single_file.expected
@@ -0,0 +1 @@
+77f7bb7e1827d7735dd1fd8bc4f4fa3ae1168a1529118c74b18f9abe69a8aecfb60fff0ecec17d2860af90e257e4fbd90048978c47fdda94f56b2ffa1d06448f  lorem_ipsum.txt
diff --git a/tests/fixtures/cksum/untagged/sha3_512_stdin.expected b/tests/fixtures/cksum/untagged/sha3_512_stdin.expected
new file mode 100644
index 000000000..57194c3ed
--- /dev/null
+++ b/tests/fixtures/cksum/untagged/sha3_512_stdin.expected
@@ -0,0 +1 @@
+77f7bb7e1827d7735dd1fd8bc4f4fa3ae1168a1529118c74b18f9abe69a8aecfb60fff0ecec17d2860af90e257e4fbd90048978c47fdda94f56b2ffa1d06448f  -