diff --git a/doc/ubuntu-dev-tools.5 b/doc/ubuntu-dev-tools.5
index 7325f86..2229e8f 100644
--- a/doc/ubuntu-dev-tools.5
+++ b/doc/ubuntu-dev-tools.5
@@ -59,8 +59,8 @@ This specifies the preferred test\-builder, one of
 
 .TP
 .B UBUNTUTOOLS_UPDATE_BUILDER
-Boolean. Whether or not to update the test\-builder before each test
-build.
+Whether or not to update the test\-builder before each test build.
+.RB "One of " yes " or " no " (default).
 
 .TP
 .B UBUNTUTOOLS_LPINSTANCE
diff --git a/ubuntutools/config.py b/ubuntutools/config.py
index 0e8bcb6..12bdafa 100644
--- a/ubuntutools/config.py
+++ b/ubuntutools/config.py
@@ -67,7 +67,7 @@ class UDTConfig(object):
             f.close()
         return config
 
-    def get_value(self, key, default=None, compat_keys=[]):
+    def get_value(self, key, default=None, boolean=False, compat_keys=[]):
         """Retrieve a value from the environment or configuration files.
         keys are prefixed with the script name, falling back to UBUNTUTOOLS for
         package-wide keys.
@@ -90,8 +90,11 @@ class UDTConfig(object):
             for store in (os.environ, self.config):
                 if k in store:
                     value = store[k]
-                    if value in ('yes', 'no'):
-                        value = value == 'yes'
+                    if boolean:
+                        if value in ('yes', 'no'):
+                            value = value == 'yes'
+                        else:
+                            continue
                     return value
         return default
 
diff --git a/ubuntutools/test/test_config.py b/ubuntutools/test/test_config.py
index 052ebd5..2d32cf2 100644
--- a/ubuntutools/test/test_config.py
+++ b/ubuntutools/test/test_config.py
@@ -83,9 +83,9 @@ REPEAT=yes
             'REPEAT': 'yes',
         })
 
-    def get_value(self, key, default=None, compat_keys=[]):
+    def get_value(self, *args, **kwargs):
         config = UDTConfig(prefix='TEST')
-        return config.get_value(key, default=default, compat_keys=compat_keys)
+        return config.get_value(*args, **kwargs)
 
     def test_defaults(self):
         self.assertEqual(self.get_value('BUILDER'), 'pbuilder')
@@ -120,9 +120,11 @@ REPEAT=yes
 
     def test_boolean(self):
         config_files['user'] = "TEST_BOOLEAN=yes"
-        self.assertEqual(self.get_value('BOOLEAN'), True)
+        self.assertEqual(self.get_value('BOOLEAN', boolean=True), True)
         config_files['user'] = "TEST_BOOLEAN=no"
-        self.assertEqual(self.get_value('BOOLEAN'), False)
+        self.assertEqual(self.get_value('BOOLEAN', boolean=True), False)
+        config_files['user'] = "TEST_BOOLEAN=true"
+        self.assertEqual(self.get_value('BOOLEAN', boolean=True), None)
 
     def test_nonpackagewide(self):
         config_files['user'] = 'UBUNTUTOOLS_FOOBAR=a'