diff --git a/bindep/depends.py b/bindep/depends.py
index faa2fe0..2ed841f 100644
--- a/bindep/depends.py
+++ b/bindep/depends.py
@@ -15,8 +15,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+import os.path
 from parsley import makeGrammar
 import subprocess
+import sys
 
 
 debversion_grammar = """
@@ -53,6 +56,50 @@ blank = ws? '\n' -> None
 """
 
 
+def get_depends(filename=None):
+    fd = get_depends_file(filename)
+    if not fd:
+        return None
+    return Depends(fd.read())
+
+
+def get_depends_file(filename=None):
+    log = logging.getLogger(__name__)
+    if filename == "-":
+        return sys.stdin
+    elif filename:
+        try:
+            fd = open(filename, 'rt')
+        except IOError:
+            log.error('Error reading file %s.' % filename)
+            return None
+    else:
+        if (os.path.isfile('bindep.txt') and
+            os.path.isfile('other-requirements.txt')):
+            log.error(
+                'Both bindep.txt and other-requirements.txt '
+                'files exist, choose one.')
+            return None
+        if os.path.isfile('bindep.txt'):
+            try:
+                fd = open('bindep.txt', 'rt')
+            except IOError:
+                log.error('Error reading file bindep.txt.')
+                return None
+        elif os.path.isfile('other-requirements.txt'):
+            try:
+                fd = open('other-requirements.txt', 'rt')
+            except IOError:
+                log.error('Error reading file other-requirements.txt.')
+                return None
+        else:
+            log.error(
+                'Neither file bindep.txt nor file '
+                'other-requirements.txt exist.')
+            return None
+    return fd
+
+
 class Depends(object):
     """Project dependencies."""
 
diff --git a/bindep/main.py b/bindep/main.py
index 6733859..5fd8280 100644
--- a/bindep/main.py
+++ b/bindep/main.py
@@ -17,7 +17,6 @@
 
 import logging
 import optparse
-import os.path
 import sys
 
 import bindep.depends
@@ -44,38 +43,9 @@ def main(depends=None):
         help="List the platform and configuration profiles.")
     opts, args = parser.parse_args()
     if depends is None:
-        if opts.filename == "-":
-            fd = sys.stdin
-        elif opts.filename:
-            try:
-                fd = open(opts.filename, 'rt')
-            except IOError:
-                logging.error('Error reading file %s.' % opts.filename)
-                return 1
-        else:
-            if (os.path.isfile('bindep.txt') and
-                os.path.isfile('other-requirements.txt')):
-                logging.error('Both bindep.txt and other-requirements.txt '
-                              'files exist, choose one.')
-                return 1
-            if os.path.isfile('bindep.txt'):
-                try:
-                    fd = open('bindep.txt', 'rt')
-                except IOError:
-                    logging.error('Error reading file bindep.txt.')
-                    return 1
-            elif os.path.isfile('other-requirements.txt'):
-                try:
-                    fd = open('other-requirements.txt', 'rt')
-                except IOError:
-                    logging.error('Error reading file other-requirements.txt.')
-                    return 1
-            else:
-                logging.error('Neither file bindep.txt nor file '
-                              'other-requirements.txt exist.')
-                return 1
-
-        depends = bindep.depends.Depends(fd.read())
+        depends = bindep.depends.get_depends(opts.filename)
+        if not depends:
+            return 1
     if opts.profiles:
         logging.info("Platform profiles:")
         for profile in depends.platform_profiles():