diff --git a/doc/ChangeLog.md b/doc/ChangeLog.md
index acbbdb84..826b2277 100644
--- a/doc/ChangeLog.md
+++ b/doc/ChangeLog.md
@@ -20,6 +20,7 @@ All notable changes to the project are documented in this file.
 ### Fixes
 - Fix containers with multiple mounts
 - Correct description for LAG LACP modes 
+- Fix #1040: Add `mount` constraint for container config 
 
 
 [v25.04.0][] - 2025-04-30
diff --git a/src/confd/yang/confd/infix-containers.yang b/src/confd/yang/confd/infix-containers.yang
index c72555ec..18974e57 100644
--- a/src/confd/yang/confd/infix-containers.yang
+++ b/src/confd/yang/confd/infix-containers.yang
@@ -22,6 +22,13 @@ module infix-containers {
     prefix infix-sys;
   }
 
+  revision 2025-05-14 {
+    description
+      "Validation improvement:
+       - Added constraint to require either 'source' or 'content' in a container mount.";
+    reference "internal";
+  }
+
   revision 2024-11-15 {
     description "Two major changes:
                   - Add support for ftp/http/https images with checksum
@@ -342,6 +349,7 @@ module infix-containers {
         }
 
         choice data {
+          mandatory true;
           case source {
             leaf source {
               description "Host path to mount in container, may be a glob.
diff --git a/src/confd/yang/confd/infix-containers@2024-11-15.yang b/src/confd/yang/confd/infix-containers@2025-05-14.yang
similarity index 100%
rename from src/confd/yang/confd/infix-containers@2024-11-15.yang
rename to src/confd/yang/confd/infix-containers@2025-05-14.yang
diff --git a/src/confd/yang/containers.inc b/src/confd/yang/containers.inc
index e6d3d8b3..b7e66044 100644
--- a/src/confd/yang/containers.inc
+++ b/src/confd/yang/containers.inc
@@ -2,5 +2,5 @@
 # REMEMBER TO UPDATE infix-interfaces ALSO IN confd.inc
 MODULES=(
     "infix-interfaces@2025-01-09.yang -e vlan-filtering -e containers"
-    "infix-containers@2024-11-15.yang"
+    "infix-containers@2025-05-14.yang"
 )