diff --git a/ipynbsrv/web/templates/web/container_snapshots/modal_create.html b/ipynbsrv/web/templates/web/container_snapshots/modal_create.html
index 8a0b991..d6647b2 100644
--- a/ipynbsrv/web/templates/web/container_snapshots/modal_create.html
+++ b/ipynbsrv/web/templates/web/container_snapshots/modal_create.html
@@ -13,7 +13,7 @@ <h4 class="modal-title">New Container Snapshot</h4>
                     <input name="ct_id" type="hidden" class="form-control" value="{{ container.id }}">
                     <div class="form-group">
                         <label for="name">Name</label>
-                        <input name="name" type="text" pattern="[A-Za-z1-9_-]+" class="form-control" required>
+                        <input name="name" type="text" pattern="^[A-z]\w*$" class="form-control" required>
                         <p class="help-block">Allowed pattern: ^[A-z]\w*$</p>
                     </div>
                     <div class="form-group">
diff --git a/ipynbsrv/web/templates/web/containers/modal_create.html b/ipynbsrv/web/templates/web/containers/modal_create.html
index f006c04..7f40fcd 100644
--- a/ipynbsrv/web/templates/web/containers/modal_create.html
+++ b/ipynbsrv/web/templates/web/containers/modal_create.html
@@ -12,7 +12,7 @@ <h4 class="modal-title">New container</h4>
                  <div class="modal-body">
                     <div class="form-group">
                         <label for="name">Name</label>
-                        <input name="name" type="text" pattern="[A-Za-z1-9_-]+" class="form-control" placeholder="e.g IPython Notebook" required>
+                        <input name="name" type="text" pattern="^[A-z]\w*$" class="form-control" placeholder="e.g IPython Notebook" required>
                         <p class="help-block">Allowed pattern: ^[A-z]\w*$</p>
                     </div>
                     <div class="form-group">
diff --git a/ipynbsrv/web/templates/web/images/modal_create.html b/ipynbsrv/web/templates/web/images/modal_create.html
index bf3fd51..3fe3b8a 100644
--- a/ipynbsrv/web/templates/web/images/modal_create.html
+++ b/ipynbsrv/web/templates/web/images/modal_create.html
@@ -21,7 +21,7 @@ <h4 class="modal-title">New image</h4>
                     </div>
                     <div class="form-group">
                         <label for="img_name">Name</label>
-                        <input name="img_name" type="text" pattern="[A-Za-z1-9_-]+" class="form-control" placeholder="e.g fhnw-maths " required>
+                        <input name="img_name" type="text" pattern="^[A-z][\w\/]*$" class="form-control" placeholder="e.g fhnw-maths " required>
                         <p class="help-block">Allowed pattern: ^[A-z][\w\/]*$</p>
                     </div>
                     <div class="form-group">