diff --git a/synthtool/__main__.py b/synthtool/__main__.py
index 12bcedb97..da1ae92af 100644
--- a/synthtool/__main__.py
+++ b/synthtool/__main__.py
@@ -12,9 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import importlib
 import os
 import sys
+import importlib.util
 from typing import List, Sequence
 
 import click
diff --git a/synthtool/gcp/common.py b/synthtool/gcp/common.py
index 5277caccc..ba050efae 100644
--- a/synthtool/gcp/common.py
+++ b/synthtool/gcp/common.py
@@ -151,12 +151,12 @@ def _load_partials(self, metadata: Dict):
             metadata["partials"] = yaml.load(f, Loader=yaml.SafeLoader)
 
 
-def decamelize(str: str):
+def decamelize(value: str):
     """ parser to convert fooBar.js to Foo Bar. """
-    str2 = str[0].upper()
-    for chr in str[1:]:
-        if re.match(r"[A-Z]", chr):
-            str2 += " " + chr.upper()
-        else:
-            str2 += chr
-    return str2
+    if not value:
+        return ""
+    str_decamelize = re.sub("^.", value[0].upper(), value)  # apple -> Apple.
+    str_decamelize = re.sub(
+        "([A-Z]+)([A-Z])([a-z0-9])", r"\1 \2\3", str_decamelize
+    )  # ACLBatman -> ACL Batman.
+    return re.sub("([a-z0-9])([A-Z])", r"\1 \2", str_decamelize)  # FooBar -> Foo Bar.
diff --git a/tests/test_common.py b/tests/test_common.py
new file mode 100644
index 000000000..f3f87f909
--- /dev/null
+++ b/tests/test_common.py
@@ -0,0 +1,31 @@
+# Copyright 2019 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from synthtool.gcp.common import decamelize
+
+
+def test_converts_camel_to_title():
+    assert decamelize("fooBar") == "Foo Bar"
+    assert decamelize("fooBarSnuh") == "Foo Bar Snuh"
+
+
+def test_handles_acronym():
+    assert decamelize("ACL") == "ACL"
+    assert decamelize("coolACL") == "Cool ACL"
+    assert decamelize("loadJSONFromGCS") == "Load JSON From GCS"
+
+
+def test_handles_empty_string():
+    assert decamelize(None) == ""
+    assert decamelize("") == ""