diff --git a/doc/configuration.rst b/doc/configuration.rst
index 0ae95638..c0119d6d 100644
--- a/doc/configuration.rst
+++ b/doc/configuration.rst
@@ -1607,8 +1607,23 @@ OSBuild Composer for building images
     * ``release`` -- release part of the final NVR. If neither this option nor
       the global ``osbuild_release`` is set, Koji will automatically generate a
       value.
-    * ``repo`` -- a list of repository URLs from which to consume packages for
+    * ``repo`` -- a list of repositories from which to consume packages for
       building the image. By default only the variant repository is used.
+      The list items may use one of the following formats:
+
+      * String with just the repository URL.
+
+      * Dictionary with the following keys:
+
+        * ``baseurl`` -- URL of the repository.
+        * ``package_sets`` -- a list of package set names to use for this
+            repository. Package sets are an internal concept of Image Builder
+            and are used in image definitions. If specified, the repository is
+            used by Image Builder only for the pipeline with the same name.
+            For example, specifying the ``build`` package set name will make
+            the repository to be used only for the build environment in which
+            the image will be built. (optional)
+
     * ``arches`` -- list of architectures for which to build the image. By
       default, the variant arches are used. This option can only restrict it,
       not add a new one.
diff --git a/pungi/checks.py b/pungi/checks.py
index 5d110c21..1b0bf201 100644
--- a/pungi/checks.py
+++ b/pungi/checks.py
@@ -1188,7 +1188,26 @@ def make_schema():
                                 },
                                 "arches": {"$ref": "#/definitions/list_of_strings"},
                                 "release": {"type": "string"},
-                                "repo": {"$ref": "#/definitions/list_of_strings"},
+                                "repo": {
+                                    "type": "array",
+                                    "items": {
+                                        "oneOf": [
+                                            {
+                                                "type": "object",
+                                                "additionalProperties": False,
+                                                "required": ["baseurl"],
+                                                "properties": {
+                                                    "baseurl": {"type": "string"},
+                                                    "package_sets": {
+                                                        "type": "array",
+                                                        "items": {"type": "string"},
+                                                    },
+                                                },
+                                            },
+                                            {"type": "string"},
+                                        ]
+                                    },
+                                },
                                 "failable": {"$ref": "#/definitions/list_of_strings"},
                                 "subvariant": {"type": "string"},
                                 "ostree_url": {"type": "string"},
diff --git a/tests/test_osbuild_phase.py b/tests/test_osbuild_phase.py
index e545a39e..a4c57817 100644
--- a/tests/test_osbuild_phase.py
+++ b/tests/test_osbuild_phase.py
@@ -251,7 +251,13 @@ class RunOSBuildThreadTest(helpers.PungiTestCase):
                 "1",  # version
                 "15",  # release
                 "image-target",
-                [self.topdir + "/compose/Everything/$arch/os"],
+                [
+                    self.topdir + "/compose/Everything/$arch/os",
+                    {
+                        "baseurl": self.topdir + "/compose/Everything/$arch/os",
+                        "package_sets": ["build"],
+                    },
+                ],
                 ["x86_64"],
             ),
             1,
@@ -273,7 +279,13 @@ class RunOSBuildThreadTest(helpers.PungiTestCase):
                     ["aarch64", "x86_64"],
                     opts={
                         "release": "15",
-                        "repo": [self.topdir + "/compose/Everything/$arch/os"],
+                        "repo": [
+                            self.topdir + "/compose/Everything/$arch/os",
+                            {
+                                "baseurl": self.topdir + "/compose/Everything/$arch/os",
+                                "package_sets": ["build"],
+                            },
+                        ],
                     },
                 ),
                 mock.call.save_task_id(1234),