diff --git a/pymacro/pymacro b/pymacro/pymacro
index e0f61c3..3820273 100755
--- a/pymacro/pymacro
+++ b/pymacro/pymacro
@@ -18,11 +18,11 @@ def get_args():
     """ Get command line arguments """
 
     import argparse
-    parser = argparse.ArgumentParser()
-    parser.add_argument("-m", "--macros", default=["macros"], action="append",
-                        help="Extra files where macros are stored")
-    parser.add_argument("-i", "--input", help="The file to be processed", default="-")
-    parser.add_argument("-o", "--output", help="The location of the output", default="-")
+    parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    parser.add_argument("-m", "--macros-file", default="macros",
+                        help="File where macros are stored")
+    parser.add_argument("-i", "--input", help="File to be processed.", default="-")
+    parser.add_argument("-o", "--output", help="Path of output", default="-")
     return parser.parse_args()
 
 
@@ -86,7 +86,10 @@ def upper_check(token, word):
 def process(input, macros):
     tokens, otf_macros = tokenize(input)
     output = tokens
-    macros = otf_macros + macros
+    macros = macros
+    
+    for key in otf_macros.keys():
+        macros[key] = otf_macros[key]
 
     for line_number, line in enumerate(tokens):
         for token_number, token in enumerate(line):
@@ -110,13 +113,10 @@ def process(input, macros):
             # will not be changed
             value = token
 
-            for macro in macros:
-                if macro[0].lower() == token.lower():
-                    value = macro[1]
-                    break
-                elif macro[0].lower() + 's' == token.lower():
-                    value = pluralize(macro[1], macro=macro)
-                    break
+            if token.lower() in macros.keys():
+                value = macros[token]
+            elif f'{token.lower()}s' in macros.keys():
+                value = pluralize(macro[1], macro=macro)
 
             output[line_number][token_number] = upper_check(token, value)
             output[line_number][token_number] += end
@@ -131,7 +131,7 @@ def tokenize(input):
     """
     tokens =  [x.split(' ') for x in input.split('\n')]
 
-    otf_macros = []
+    otf_macros = {}
     in_otf_macro = False
     tmp_macro_keyword = None
     tmp_macro_definition = []
@@ -151,7 +151,7 @@ def tokenize(input):
                 split_token = re.split(r',.|.,', token)
                 tmp_macro_definition.append(split_token[0])
                 tokens[line_index][token_index] = tmp_macro_keyword + split_token[1]
-                otf_macros.append((tmp_macro_keyword, ' '.join(tmp_macro_definition)))
+                otf_macros[tmp_macro_keyword] = ' '.join(tmp_macro_definition)
                 in_otf_macro = False
                 continue
             elif in_otf_macro:
@@ -193,18 +193,22 @@ def get_macros(input):
     """
     Turn a macros string into a list of tuples of macros
     """
-    response = []
+    response = {}
 
-    # turn input into unvalidated list of macros
+    # turn input into list of tuples
     macros = [re.split('[\t]', x) for x in input.split('\n')]
 
-    # validate macros
+    # check if keyword is `source`, get macros from sourced file if it is
     for index, macro in enumerate(macros):
         if macro[0] == "source":
             with open(macro[1]) as file:
-                response += get_macros(file.read())
+                macros += get_macros(file.read())
+                macros[index] = ()
+
+    # store macros as dict and return
+    for index, macro in enumerate(macros):
         if len(macro) >= 2:
-            response.append(tuple(macros[index]))
+            response[macro[0].lower()] = macro[1]
 
     return response
 
@@ -237,10 +241,8 @@ def main(args):
 
     # get macros
 
-    macros = []
-    for macro_file in args.macros:
-        with open(macro_file) as file:
-            macros += get_macros(file.read())
+    with open(args.macros_file) as file:
+        macros = get_macros(file.read())
 
     # get tokens (file contents)
     if args.input == "-":