diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 84e057cef..e50a9b8ae 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -13,6 +13,11 @@ Unreleased
 * scrooge-generator: Java throws an exception when encountering incorrect field
   types in a struct while deserializing. ``PHAB_ID=D565373``
 
+* scrooge-generator: Scrooge no longer fails to parse Thrift IDL when annotations are used
+  on the individual components of a 'container type' (e.g. list, set, map). Those types of
+  annotations are not currently used by scrooge, instead they are skipped over and discarded,
+  but the IDL no longer fails to parse when they are encountered. ``PHAB_ID=D583284``
+
 20.10.0
 -------
 
diff --git a/scrooge-generator-tests/src/test/scala/com/twitter/scrooge/frontend/ThriftParserSpec.scala b/scrooge-generator-tests/src/test/scala/com/twitter/scrooge/frontend/ThriftParserSpec.scala
index 6c845f82d..31d5d2cef 100644
--- a/scrooge-generator-tests/src/test/scala/com/twitter/scrooge/frontend/ThriftParserSpec.scala
+++ b/scrooge-generator-tests/src/test/scala/com/twitter/scrooge/frontend/ThriftParserSpec.scala
@@ -96,17 +96,40 @@ struct MyStruct {}
       parser.parse("binary", parser.fieldType) must be(TBinary)
     }
 
-    "compound types" in {
+    "list types" in {
       parser.parse("list<i64>", parser.fieldType) must be(ListType(TI64, None))
       parser.parse("list<list<string>>", parser.fieldType) must be(
         ListType(ListType(TString, None), None)
       )
-      parser.parse("map<string, list<bool>>", parser.fieldType) must be(
-        MapType(TString, ListType(TBool, None), None)
+      // Annotations within container type definitions are parsed properly, but thrown away
+      parser.parse("list < i64 (something = \"else\") >", parser.fieldType) must be(
+        ListType(TI64, None))
+      parser.parse("list<list<string (a = \"b\")>(c = \"d\")>", parser.fieldType) must be(
+        ListType(ListType(TString, None), None)
       )
+    }
+
+    "set types" in {
       parser.parse("set<Monster>", parser.fieldType) must be(
         SetType(ReferenceType(Identifier("Monster")), None)
       )
+      parser.parse("set<bool (hello = \"goodbye\")>", parser.fieldType) must be(
+        SetType(TBool, None)
+      )
+    }
+
+    "map types" in {
+      parser.parse("map<string, list<bool>>", parser.fieldType) must be(
+        MapType(TString, ListType(TBool, None), None)
+      )
+      parser.parse(
+        "map<string (a=\"b\"), list<bool (c=\"d\")> (e=\"f\")>",
+        parser.fieldType) must be(
+        MapType(TString, ListType(TBool, None), None)
+      )
+    }
+
+    "compound types" in {
       parser.parse("Monster", parser.fieldType) must be(ReferenceType(Identifier("Monster")))
     }
 
@@ -833,8 +856,17 @@ enum Foo
         )
       )
 
-      // TODO(CSL-4127): support annotations on nested types
-      // parser.parse("""typedef list< double ( cpp.fixed_point = "16" ) > tiny_float_list""", parser.typedef) must be()
+      parser.parse(
+        """typedef list< double ( cpp.fixed_point = "16" ) > tiny_float_list""",
+        parser.typedef
+      ) must be(
+        Typedef(
+          SimpleID("tiny_float_list", None),
+          ListType(TDouble, None),
+          Map(),
+          Map()
+        )
+      )
 
       parser.parse(
         """
diff --git a/scrooge-generator/src/main/scala/com/twitter/scrooge/frontend/ThriftParser.scala b/scrooge-generator/src/main/scala/com/twitter/scrooge/frontend/ThriftParser.scala
index f6c1b500e..6c2533dc3 100644
--- a/scrooge-generator/src/main/scala/com/twitter/scrooge/frontend/ThriftParser.scala
+++ b/scrooge-generator/src/main/scala/com/twitter/scrooge/frontend/ThriftParser.scala
@@ -201,18 +201,25 @@ class ThriftParser(
 
   lazy val containerType: Parser[ContainerType] = mapType | setType | listType
 
+  // Annotations within container types are parsed correctly, but currently thrown away
   lazy val mapType: Parser[MapType] =
-    ("map" ~> opt(cppType) <~ "<") ~ (fieldType <~ ",") ~ (fieldType <~ ">") ^^ {
+    ("map" ~> opt(cppType) <~ "<") ~
+      (fieldType <~ defaultedAnnotations <~ ",") ~
+      (fieldType <~ defaultedAnnotations <~ ">") ^^ {
       case cpp ~ key ~ value => MapType(key, value, cpp)
     }
 
-  lazy val setType: Parser[SetType] = ("set" ~> opt(cppType)) ~ ("<" ~> fieldType <~ ">") ^^ {
-    case cpp ~ t => SetType(t, cpp)
-  }
+  // Annotations within container types are parsed correctly, but currently thrown away
+  lazy val setType: Parser[SetType] =
+    ("set" ~> opt(cppType)) ~ ("<" ~> fieldType <~ defaultedAnnotations <~ ">") ^^ {
+      case cpp ~ t => SetType(t, cpp)
+    }
 
-  lazy val listType: Parser[ListType] = ("list" ~ "<") ~> (fieldType <~ ">") ~ opt(cppType) ^^ {
-    case t ~ cpp => ListType(t, cpp)
-  }
+  // Annotations within container types are parsed correctly, but currently thrown away
+  lazy val listType: Parser[ListType] =
+    ("list" ~ "<") ~> (fieldType <~ defaultedAnnotations <~ ">") ~ opt(cppType) ^^ {
+      case t ~ cpp => ListType(t, cpp)
+    }
 
   // FFS. i'm very close to removing this and forcably breaking old thrift files.
   lazy val cppType: Parser[String] = "cpp_type" ~> stringLiteral ^^ { literal => literal.value }