diff --git a/core/src/main/python/wlsdeploy/util/cla_helper.py b/core/src/main/python/wlsdeploy/util/cla_helper.py
index 44f6fcf94..b4e3c3120 100644
--- a/core/src/main/python/wlsdeploy/util/cla_helper.py
+++ b/core/src/main/python/wlsdeploy/util/cla_helper.py
@@ -383,10 +383,8 @@ def _get_merge_match_key(key, variable_map):
     :param variable_map: variable map to use for substitutions
     :return: the key to use for matching
     """
-    if variable_map is not None:
-        match_key = variables.substitute_key(key, variable_map)
-    else:
-        match_key = key
+
+    match_key = variables.substitute_key(key, variable_map)
 
     if model_helper.is_delete_name(match_key):
         match_key = model_helper.get_delete_item_name(match_key)
diff --git a/core/src/main/python/wlsdeploy/util/variables.py b/core/src/main/python/wlsdeploy/util/variables.py
index 9c81de0f1..6d759bfbd 100644
--- a/core/src/main/python/wlsdeploy/util/variables.py
+++ b/core/src/main/python/wlsdeploy/util/variables.py
@@ -446,11 +446,24 @@ def substitute_key(text, variables):
     :param variables: the variable map
     :return: the substituted text value
     """
-    matches = _property_pattern.findall(text)
+    method_name = "substitute_key"
+
+    if variables is not None:
+        matches = _property_pattern.findall(text)
+        for token, key in matches:
+            if key in variables:
+                value = variables[key]
+                text = text.replace(token, value)
+
+    matches = _environment_pattern.findall(text)
     for token, key in matches:
-        if key in variables:
-            value = variables[key]
-            text = text.replace(token, value)
+        # log, or throw an exception if key is not found.
+        if not os.environ.has_key(key):
+            continue
+
+        value = os.environ.get(key)
+        text = text.replace(token, value)
+
     return text
 
 
diff --git a/core/src/test/python/wlsdeploy/util/cla_helper_test.py b/core/src/test/python/wlsdeploy/util/cla_helper_test.py
index cb07a8403..d50054e04 100644
--- a/core/src/test/python/wlsdeploy/util/cla_helper_test.py
+++ b/core/src/test/python/wlsdeploy/util/cla_helper_test.py
@@ -60,6 +60,7 @@ def testMergeModels(self):
         }
 
         variables = {}
+
         cla_helper.merge_model_dictionaries(dictionary, new_dictionary, variables)
         # print("Merged model: " + str(dictionary))