diff --git a/components/kdrv/apps/include/kdrv_slot.h b/components/kdrv/apps/include/kdrv_slot.h
index cad1617..8ca20df 100644
--- a/components/kdrv/apps/include/kdrv_slot.h
+++ b/components/kdrv/apps/include/kdrv_slot.h
@@ -65,7 +65,16 @@ kode_status_t kdrv_slot_begin(void);
 /** @brief Append to the open session. */
 kode_status_t kdrv_slot_write(const void *data, size_t len);
 
-/** @brief Close the session and verify what was written. */
+/**
+ * @brief Close the session and verify what was written.
+ *
+ * An image is taken only when it is sound and its description names the
+ * project that is running: the slot is this firmware's own update, and an
+ * app's image there would boot in its place.
+ *
+ * @return KODE_OK; KODE_DENIED with no session open; KODE_ERROR for an image
+ *         that fails its checks, has no description or is another project's.
+ */
 kode_status_t kdrv_slot_end(void);
 
 /** @brief Abandon the session, leaving the slot invalid. */
diff --git a/components/kdrv/apps/src/kdrv_slot.c b/components/kdrv/apps/src/kdrv_slot.c
index 3c5e10f..b3559d8 100644
--- a/components/kdrv/apps/src/kdrv_slot.c
+++ b/components/kdrv/apps/src/kdrv_slot.c
@@ -181,6 +181,41 @@ kode_status_t kdrv_slot_write(const void *data, size_t len)
     return KODE_OK;
 }
 
+/**
+ * @brief Tell whether the image in the slot is the project that is running.
+ *
+ * The slot is where this firmware's own update goes, and the next boot hands
+ * the board to whatever it holds. esp_ota_end() accepts any image built for
+ * the chip, an app's included, so the project's name is what tells an update
+ * from something else.
+ *
+ * @return KODE_OK; KODE_ERROR when the slot's description cannot be read or
+ *         names another project.
+ */
+static kode_status_t slot_is_ours(void)
+{
+    const esp_partition_t * const p   = slot_part();
+    const esp_app_desc_t  * const run = esp_app_get_description();
+    esp_app_desc_t                desc;
+
+    if ( (NULL == p) || (NULL == run)
+        || (esp_ota_get_partition_description(p, &desc) != ESP_OK) )
+    {
+        KLOG_E(TAG, "the image written has no description to read; "
+                    "it is not an update");
+        return KODE_ERROR;
+    }
+    if ( strncmp(desc.project_name, run->project_name,
+                 sizeof(desc.project_name)) != 0 )
+    {
+        KLOG_E(TAG, "the image written is '%.*s', not %s; it is not an update",
+               (int)sizeof(desc.project_name), desc.project_name,
+               run->project_name);
+        return KODE_ERROR;
+    }
+    return KODE_OK;
+}
+
 kode_status_t kdrv_slot_end(void)
 {
     if ( 0 == s_ota )
@@ -194,7 +229,7 @@ kode_status_t kdrv_slot_end(void)
         KLOG_E(TAG, "esp_ota_end: %s", esp_err_to_name(err));
         return KODE_ERROR;
     }
-    return KODE_OK;
+    return slot_is_ours();
 }
 
 void kdrv_slot_abort(void)
@@ -251,7 +286,7 @@ static kode_status_t slot_sink_write(void *ctx, const void *data, size_t len)
  * @brief Close the slot's OTA session and verify what was written.
  * @param ctx Unused.
  * @return KODE_OK; KODE_DENIED with no session open; KODE_ERROR when
- *         esp_ota_end() refuses the image.
+ *         kdrv_slot_end() refuses the image.
  */
 static kode_status_t slot_sink_end(void *ctx)
 {
diff --git a/tests/host_slot/cases/test_kdrv_slot.c b/tests/host_slot/cases/test_kdrv_slot.c
index 2d25afb..c0421e2 100644
--- a/tests/host_slot/cases/test_kdrv_slot.c
+++ b/tests/host_slot/cases/test_kdrv_slot.c
@@ -733,6 +733,65 @@ static void expect_desc(esp_app_desc_t *desc, const char *project)
     esp_ota_get_partition_description_ReturnThruPtr_app_desc(desc);
 }
 
+/* The slot is where this firmware's own update goes, and the next boot hands
+ * the board to whatever it holds. What esp_ota_end() accepts is any image
+ * built for the chip, an app's included, so the project's name is what tells
+ * an update from something else. */
+TEST_CASE("an image of the running project ends well", "[kdrv_slot]")
+{
+    esp_app_desc_t   desc;
+    kdrv_slot_desc_t running;
+
+    slot_fresh(ESP_PARTITION_SUBTYPE_APP_OTA_0);
+    TEST_ASSERT_EQUAL_INT(KODE_OK, kdrv_running_desc(&running));
+
+    expect_begin_ok();
+    TEST_ASSERT_EQUAL_INT(KODE_OK, kdrv_slot_begin());
+
+    esp_ota_end_ExpectAnyArgsAndReturn(ESP_OK);
+    expect_desc(&desc, running.project);
+    TEST_ASSERT_EQUAL_INT(KODE_OK, kdrv_slot_end());
+
+    slot_done();
+}
+
+TEST_CASE("an image of another project is refused at the end", "[kdrv_slot]")
+{
+    esp_app_desc_t desc;
+
+    slot_fresh(ESP_PARTITION_SUBTYPE_APP_OTA_0);
+
+    expect_begin_ok();
+    TEST_ASSERT_EQUAL_INT(KODE_OK, kdrv_slot_begin());
+
+    esp_ota_end_ExpectAnyArgsAndReturn(ESP_OK);
+    expect_desc(&desc, "buttons_led");
+    TEST_ASSERT_EQUAL_INT_MESSAGE(KODE_ERROR, kdrv_slot_end(),
+        "an app's image in the slot would boot in the OS's place");
+
+    /* The session is over all the same, and a new one opens. */
+    TEST_ASSERT_EQUAL_INT(KODE_DENIED, kdrv_slot_end());
+    expect_begin_ok();
+    TEST_ASSERT_EQUAL_INT(KODE_OK, kdrv_slot_begin());
+
+    slot_done();
+}
+
+TEST_CASE("an image with no description to read is refused at the end",
+          "[kdrv_slot]")
+{
+    slot_fresh(ESP_PARTITION_SUBTYPE_APP_OTA_0);
+
+    expect_begin_ok();
+    TEST_ASSERT_EQUAL_INT(KODE_OK, kdrv_slot_begin());
+
+    esp_ota_end_ExpectAnyArgsAndReturn(ESP_OK);
+    esp_ota_get_partition_description_ExpectAnyArgsAndReturn(ESP_ERR_NOT_FOUND);
+    TEST_ASSERT_EQUAL_INT(KODE_ERROR, kdrv_slot_end());
+
+    slot_done();
+}
+
 TEST_CASE("every app partition can be described by id, and only the running "
           "one says so", "[kdrv_slot]")
 {
diff --git a/tests/host_slot/main/CMakeLists.txt b/tests/host_slot/main/CMakeLists.txt
index 11cbf71..21c6f82 100644
--- a/tests/host_slot/main/CMakeLists.txt
+++ b/tests/host_slot/main/CMakeLists.txt
@@ -11,6 +11,7 @@ file(GLOB khal_includes LIST_DIRECTORIES true "${SDK_DIR}/components/khal/*/incl
 idf_component_register(
     SRCS "runner.c"
          "log_stub.c"
+         "app_desc_stub.c"
          ${CASE_SOURCES}
          "${SDK_DIR}/components/kdrv/apps/src/kdrv_slot.c"
     INCLUDE_DIRS "."
diff --git a/tests/host_slot/main/app_desc_stub.c b/tests/host_slot/main/app_desc_stub.c
new file mode 100644
index 0000000..96d24f0
--- /dev/null
+++ b/tests/host_slot/main/app_desc_stub.c
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/**
+ * @file app_desc_stub.c
+ * @brief The running image's description, for a binary the linux target
+ *        links none into.
+ */
+#include "esp_app_desc.h"
+
+/** @brief What the running image says it is: the project an update must name. */
+static const esp_app_desc_t s_desc = {
+    .project_name = "kodeos",
+    .version      = "0.0.0",
+};
+
+const esp_app_desc_t *esp_app_get_description(void)
+{
+    return &s_desc;
+}