diff --git a/AK/Tests/TestBase64.cpp b/AK/Tests/TestBase64.cpp
index 40b7e494a6..d495d79092 100644
--- a/AK/Tests/TestBase64.cpp
+++ b/AK/Tests/TestBase64.cpp
@@ -30,6 +30,22 @@
 #include <AK/ByteBuffer.h>
 #include <AK/String.h>
 
+TEST_CASE(test_decode)
+{
+    auto decode_equal = [&](const char* input, const char* expected) {
+        auto decoded = decode_base64(StringView(input));
+        EXPECT(String::copy(decoded) == String(expected));
+    };
+
+    decode_equal("", "");
+    decode_equal("Zg==", "f");
+    decode_equal("Zm8=", "fo");
+    decode_equal("Zm9v", "foo");
+    decode_equal("Zm9vYg==", "foob");
+    decode_equal("Zm9vYmE=", "fooba");
+    decode_equal("Zm9vYmFy", "foobar");
+}
+
 TEST_CASE(test_encode)
 {
     auto encode_equal = [&](const char* input, const char* expected) {