diff --git a/src/workerd/util/mimetype-test.c++ b/src/workerd/util/mimetype-test.c++
index 87a52310c86..7e26af3ede5 100644
--- a/src/workerd/util/mimetype-test.c++
+++ b/src/workerd/util/mimetype-test.c++
@@ -464,6 +464,23 @@ KJ_TEST("Quoted-string escape handling") {
   }
 }
 
+KJ_TEST("AWS JSON MIME types are classified as text") {
+  static constexpr kj::StringPtr supportedTypes[] = {
+    "application/x-amz-json-1.0"_kj,
+    "application/x-amz-json-1.1"_kj,
+  };
+
+  for (const auto& input: supportedTypes) {
+    auto mimeType = KJ_ASSERT_NONNULL(MimeType::tryParse(input));
+    KJ_ASSERT(MimeType::isText(mimeType));
+    KJ_ASSERT(!MimeType::isJson(mimeType));
+  }
+
+  auto unsupportedType = KJ_ASSERT_NONNULL(MimeType::tryParse("application/x-amz-json-1.2"_kj));
+  KJ_ASSERT(!MimeType::isText(unsupportedType));
+  KJ_ASSERT(!MimeType::isJson(unsupportedType));
+}
+
 KJ_TEST("Backslash escaping in serialization round-trips") {
   // A value containing both backslash and non-token chars must be quoted
   // with the backslash escaped, and the result must round-trip.
diff --git a/src/workerd/util/mimetype.h b/src/workerd/util/mimetype.h
index 1c4b9dac31a..c4e3606b66c 100644
--- a/src/workerd/util/mimetype.h
+++ b/src/workerd/util/mimetype.h
@@ -146,7 +146,8 @@ class MimeType final {
     auto type = mimeType.type();
     auto subtype = mimeType.subtype();
     return type == "text" || isXml(mimeType) || isJson(mimeType) || isJavascript(mimeType) ||
-        (type == "application" && subtype == "dns-json");
+        (type == "application" &&
+            (subtype == "dns-json" || subtype == "x-amz-json-1.0" || subtype == "x-amz-json-1.1"));
   }
 
   template <IsMimeType T>