diff --git a/tests/parser/syntax/test_byte_string.py b/tests/parser/syntax/test_byte_string.py
deleted file mode 100644
index 90bbe197b0..0000000000
--- a/tests/parser/syntax/test_byte_string.py
+++ /dev/null
@@ -1,26 +0,0 @@
-import pytest
-
-from vyper import compiler
-
-valid_list = [
-    """
-@external
-def foo() -> String[10]:
-    return "badminton"
-    """,
-    """
-@external
-def foo():
-    x: String[11] = "¡très bien!"
-    """,
-    """
-@external
-def test() -> String[100]:
-    return "hello world!"
-    """,
-]
-
-
-@pytest.mark.parametrize("good_code", valid_list)
-def test_byte_string_success(good_code):
-    assert compiler.compile_code(good_code) is not None
diff --git a/tests/parser/syntax/test_bytes.py b/tests/parser/syntax/test_bytes.py
index d732ec3ea5..a7fb7e77ce 100644
--- a/tests/parser/syntax/test_bytes.py
+++ b/tests/parser/syntax/test_bytes.py
@@ -1,7 +1,13 @@
 import pytest
 
 from vyper import compiler
-from vyper.exceptions import InvalidOperation, InvalidType, SyntaxException, TypeMismatch
+from vyper.exceptions import (
+    InvalidOperation,
+    InvalidType,
+    StructureException,
+    SyntaxException,
+    TypeMismatch,
+)
 
 fail_list = [
     (
@@ -77,6 +83,14 @@ def test() -> Bytes[1]:
     """,
         SyntaxException,
     ),
+    (
+        """
+@external
+def foo():
+    a: Bytes = b"abc"
+    """,
+        StructureException,
+    ),
 ]
 
 
diff --git a/tests/parser/syntax/test_dynamic_array.py b/tests/parser/syntax/test_dynamic_array.py
index e7dc2d1183..0c23bf67da 100644
--- a/tests/parser/syntax/test_dynamic_array.py
+++ b/tests/parser/syntax/test_dynamic_array.py
@@ -16,6 +16,14 @@
     """,
         StructureException,
     ),
+    (
+        """
+@external
+def foo():
+    a: DynArray = [1, 2, 3]
+    """,
+        StructureException,
+    ),
 ]
 
 
diff --git a/tests/parser/syntax/test_invalids.py b/tests/parser/syntax/test_invalids.py
index 3c51075e60..33478fcff1 100644
--- a/tests/parser/syntax/test_invalids.py
+++ b/tests/parser/syntax/test_invalids.py
@@ -363,6 +363,13 @@ def a():
     UnknownAttribute,
 )
 
+must_fail(
+    """
+a: HashMap
+""",
+    StructureException,
+)
+
 
 @pytest.mark.parametrize("bad_code,exception_type", fail_list)
 def test_compilation_fails_with_exception(bad_code, exception_type):
diff --git a/tests/parser/syntax/test_string.py b/tests/parser/syntax/test_string.py
index 5b5b9e5bb5..6252011bd9 100644
--- a/tests/parser/syntax/test_string.py
+++ b/tests/parser/syntax/test_string.py
@@ -1,6 +1,7 @@
 import pytest
 
 from vyper import compiler
+from vyper.exceptions import StructureException
 
 valid_list = [
     """
@@ -27,9 +28,31 @@ def foo() -> bool:
     y: String[12] = "test"
     return x != y
     """,
+    """
+@external
+def test() -> String[100]:
+    return "hello world!"
+    """,
 ]
 
 
 @pytest.mark.parametrize("good_code", valid_list)
 def test_string_success(good_code):
     assert compiler.compile_code(good_code) is not None
+
+
+invalid_list = [
+    (
+        """
+@external
+def foo():
+    a: String = "abc"
+    """,
+        StructureException,
+    )
+]
+
+
+@pytest.mark.parametrize("bad_code,exc", invalid_list)
+def test_string_fail(assert_compile_failed, get_contract_with_gas_estimation, bad_code, exc):
+    assert_compile_failed(lambda: get_contract_with_gas_estimation(bad_code), exc)
diff --git a/vyper/semantics/types/utils.py b/vyper/semantics/types/utils.py
index 6ae677e451..1549684460 100644
--- a/vyper/semantics/types/utils.py
+++ b/vyper/semantics/types/utils.py
@@ -104,7 +104,14 @@ def _failwith(type_name):
     if node.id not in namespace:
         _failwith(node.node_source_code)
 
-    return namespace[node.id]
+    typ_ = namespace[node.id]
+    if hasattr(typ_, "from_annotation"):
+        # cases where the object in the namespace is an uninstantiated
+        # type object, ex. Bytestring or DynArray (with no length provided).
+        # call from_annotation to produce a better error message.
+        typ_.from_annotation(node)
+
+    return typ_
 
 
 def get_index_value(node: vy_ast.Index) -> int: