diff --git a/pungi/compose.py b/pungi/compose.py
index 2c828c2d..4c4523bb 100644
--- a/pungi/compose.py
+++ b/pungi/compose.py
@@ -290,7 +290,7 @@ class Compose(kobo.log.LoggingBase):
 
         :raises RuntimeError: when unknown ``disc_type`` is given
         """
-        default_format = "%(compose_id)s-%(variant)s-%(arch)s-%(disc_type)s%(disc_num)s%(suffix)s"
+        default_format = "{compose_id}-{variant}-{arch}-{disc_type}{disc_num}{suffix}"
         format = format or self.conf.get('image_name_format', default_format)
 
         if arch == "src":
@@ -312,7 +312,7 @@ class Compose(kobo.log.LoggingBase):
                                  disc_num=disc_num,
                                  suffix=suffix)
         try:
-            return format % args
+            return (format % args).format(**args)
         except KeyError as err:
             raise RuntimeError('Failed to create image name: unknown format element: %s' % err.message)
 
diff --git a/pungi/phases/image_checksum.py b/pungi/phases/image_checksum.py
index aa74c4fa..40bab8ec 100644
--- a/pungi/phases/image_checksum.py
+++ b/pungi/phases/image_checksum.py
@@ -74,7 +74,7 @@ class ImageChecksumPhase(PhaseBase):
         base_checksum_name = self.compose.conf.get('media_checksum_base_filename', '')
         if base_checksum_name:
             substs = get_format_substs(self.compose, variant=variant, arch=arch)
-            base_checksum_name = base_checksum_name % substs
+            base_checksum_name = (base_checksum_name % substs).format(**substs)
             base_checksum_name += '-'
         return base_checksum_name
 
diff --git a/pungi/util.py b/pungi/util.py
index b5024cb9..13a3fdbf 100644
--- a/pungi/util.py
+++ b/pungi/util.py
@@ -354,13 +354,13 @@ def get_volid(compose, arch, variant=None, escape_spaces=False, disc_type=False)
         variant_uid = variant and variant.uid or None
 
     products = [
-        "%(release_short)s-%(version)s %(variant)s.%(arch)s",
-        "%(release_short)s-%(version)s %(arch)s",
+        "{release_short}-{version} {variant}.{arch}",
+        "{release_short}-{version} {arch}",
     ]
     products = compose.conf.get('image_volid_formats', products)
     layered_products = [
-        "%(release_short)s-%(version)s %(base_product_short)s-%(base_product_version)s %(variant)s.%(arch)s",
-        "%(release_short)s-%(version)s %(base_product_short)s-%(base_product_version)s %(arch)s",
+        "{release_short}-{version} {base_product_short}-{base_product_version} {variant}.{arch}",
+        "{release_short}-{version} {base_product_short}-{base_product_version} {arch}",
     ]
     layered_products = compose.conf.get('image_volid_layered_product_formats', layered_products)
 
@@ -374,14 +374,15 @@ def get_volid(compose, arch, variant=None, escape_spaces=False, disc_type=False)
         if not variant_uid and "%(variant)s" in i:
             continue
         try:
-            volid = i % get_format_substs(compose,
-                                          variant=variant_uid,
-                                          release_short=release_short,
-                                          version=release_version,
-                                          arch=arch,
-                                          disc_type=disc_type or '',
-                                          base_product_short=base_product_short,
-                                          base_product_version=base_product_version)
+            args = get_format_substs(compose,
+                                     variant=variant_uid,
+                                     release_short=release_short,
+                                     version=release_version,
+                                     arch=arch,
+                                     disc_type=disc_type or '',
+                                     base_product_short=base_product_short,
+                                     base_product_version=base_product_version)
+            volid = (i % args).format(**args)
         except KeyError as err:
             raise RuntimeError('Failed to create volume id: unknown format element: %s' % err.message)
         volid = _apply_substitutions(compose, volid)
diff --git a/tests/test_imagechecksumphase.py b/tests/test_imagechecksumphase.py
index 30d1f856..005ff7ac 100755
--- a/tests/test_imagechecksumphase.py
+++ b/tests/test_imagechecksumphase.py
@@ -137,6 +137,38 @@ class TestImageChecksumPhase(PungiTestCase):
                                                      mock.call(None, 'md5', 'cafebabe')],
                                                     any_order=True)
 
+    @mock.patch('os.path.exists')
+    @mock.patch('kobo.shortcuts.compute_file_checksums')
+    @mock.patch('pungi.phases.image_checksum.dump_checksums')
+    def test_checksum_save_individuals_custom_name_str_format(self, dump, cc, exists):
+        compose = DummyCompose(self.topdir, {
+            'media_checksums': ['md5', 'sha256'],
+            'media_checksum_base_filename': '{release_short}-{variant}-{version}-{date}{type_suffix}.{respin}'
+        })
+
+        phase = ImageChecksumPhase(compose)
+
+        exists.return_value = True
+        cc.return_value = {'md5': 'cafebabe', 'sha256': 'deadbeef'}
+
+        phase.run()
+
+        dump.assert_has_calls(
+            [mock.call(self.topdir + '/compose/Client/i386/iso', 'md5',
+                       {'image.iso': 'cafebabe'}, 'image.iso.MD5SUM'),
+             mock.call(self.topdir + '/compose/Client/i386/iso', 'sha256',
+                       {'image.iso': 'deadbeef'}, 'image.iso.SHA256SUM'),
+             mock.call(self.topdir + '/compose/Client/i386/iso', 'md5', {'image.iso': 'cafebabe'},
+                       'test-Client-1.0-20151203.t.0-MD5SUM'),
+             mock.call(self.topdir + '/compose/Client/i386/iso', 'sha256', {'image.iso': 'deadbeef'},
+                       'test-Client-1.0-20151203.t.0-SHA256SUM')],
+            any_order=True
+        )
+        cc.assert_called_once_with(self.topdir + '/compose/Client/i386/iso/image.iso', ['md5', 'sha256'])
+        compose.image.add_checksum.assert_has_calls([mock.call(None, 'sha256', 'deadbeef'),
+                                                     mock.call(None, 'md5', 'cafebabe')],
+                                                    any_order=True)
+
 
 class TestChecksums(unittest.TestCase):
     def setUp(self):