diff --git a/src/pretix/presale/templates/pretixpresale/event/fragment_product_list.html b/src/pretix/presale/templates/pretixpresale/event/fragment_product_list.html
index bb9d93f3f..1502b68e1 100644
--- a/src/pretix/presale/templates/pretixpresale/event/fragment_product_list.html
+++ b/src/pretix/presale/templates/pretixpresale/event/fragment_product_list.html
@@ -198,7 +198,8 @@
                                             </label>
                                         {% else %}
                                             <div class="input-item-count-group">
-                                                <button type="button" data-step="-1" data-controls="variation_{{ item.id }}_{{ var.id }}" class="btn btn-default input-item-count-dec" aria-label="{% trans "Decrease quantity" %}">-</button>
+                                                <button type="button" data-step="-1" data-controls="variation_{{ item.id }}_{{ var.id }}" class="btn btn-default input-item-count-dec" aria-label="{% trans "Decrease quantity" %}"
+                                                    {% if not ev.presale_is_running %}disabled{% endif %}>-</button>
                                                 <input type="number" class="form-control input-item-count" placeholder="0" min="0"
                                                        {% if not ev.presale_is_running %}disabled{% endif %}
                                                         {% if item.free_price %}
@@ -208,7 +209,8 @@
                                                        id="variation_{{ item.id }}_{{ var.id }}"
                                                        name="variation_{{ item.id }}_{{ var.id }}"
                                                        aria-label="{% blocktrans with item=item.name var=var.name %}Quantity of {{ item }}, {{ var }} to order{% endblocktrans %}">
-                                                <button type="button" data-step="1" data-controls="variation_{{ item.id }}_{{ var.id }}" class="btn btn-default input-item-count-inc" aria-label="{% trans "Increase quantity" %}">+</button>
+                                                <button type="button" data-step="1" data-controls="variation_{{ item.id }}_{{ var.id }}" class="btn btn-default input-item-count-inc" aria-label="{% trans "Increase quantity" %}"
+                                                    {% if not ev.presale_is_running %}disabled{% endif %}>+</button>
                                             </div>
                                         {% endif %}
                                     </div>
@@ -339,7 +341,8 @@
                                 </label>
                             {% else %}
                                 <div class="input-item-count-group">
-                                    <button type="button" data-step="-1" data-controls="item_{{ item.id }}" class="btn btn-default input-item-count-dec" aria-label="{% trans "Decrease quantity" %}">-</button>
+                                    <button type="button" data-step="-1" data-controls="item_{{ item.id }}" class="btn btn-default input-item-count-dec" aria-label="{% trans "Decrease quantity" %}"
+                                        {% if not ev.presale_is_running %}disabled{% endif %}>-</button>
                                     <input type="number" class="form-control input-item-count" placeholder="0" min="0"
                                            {% if not ev.presale_is_running %}disabled{% endif %}
                                            {% if itemnum == 1 %}value="1"{% endif %}
@@ -351,7 +354,8 @@
                                            id="item_{{ item.id }}"
                                            aria-label="{% blocktrans with item=item.name %}Quantity of {{ item }} to order{% endblocktrans %}"
                                            {% if item.description %} aria-describedby="item-{{ item.id }}-description"{% endif %}>
-                                    <button type="button" data-step="1" data-controls="item_{{ item.id }}" class="btn btn-default input-item-count-inc" aria-label="{% trans "Increase quantity" %}">+</button>
+                                    <button type="button" data-step="1" data-controls="item_{{ item.id }}" class="btn btn-default input-item-count-inc" aria-label="{% trans "Increase quantity" %}"
+                                        {% if not ev.presale_is_running %}disabled{% endif %}>+</button>
                                 </div>
                             {% endif %}
                         </div>
diff --git a/src/pretix/static/pretixpresale/js/ui/main.js b/src/pretix/static/pretixpresale/js/ui/main.js
index 22077e0cc..11b488e0e 100644
--- a/src/pretix/static/pretixpresale/js/ui/main.js
+++ b/src/pretix/static/pretixpresale/js/ui/main.js
@@ -122,7 +122,7 @@ var form_handlers = function (el) {
         var step = parseFloat(this.getAttribute("data-step"));
         var controls = document.getElementById(this.getAttribute("data-controls"));
         var currentValue = parseFloat(controls.value);
-        controls.value = Math.max(controls.min, Math.min(controls.max, (currentValue || 0) + step));
+        controls.value = Math.max(controls.min, Math.min(controls.max || Number.MAX_SAFE_INTEGER, (currentValue || 0) + step));
         controls.dispatchEvent(new Event("change"));
     });
 
diff --git a/src/pretix/static/pretixpresale/js/widget/widget.js b/src/pretix/static/pretixpresale/js/widget/widget.js
index 6b7fc98e8..66cf2e6c4 100644
--- a/src/pretix/static/pretixpresale/js/widget/widget.js
+++ b/src/pretix/static/pretixpresale/js/widget/widget.js
@@ -317,7 +317,7 @@ Vue.component('availbox', {
             var t = e.target.tagName == 'BUTTON' ? e.target : e.target.closest('button');
             var step = parseFloat(t.getAttribute("data-step"));
             var controls = document.getElementById(t.getAttribute("data-controls"));
-            this.amount_selected = Math.max(controls.min, Math.min(controls.max, (this.amount_selected || 0) + step));
+            this.amount_selected = Math.max(controls.min, Math.min(controls.max || Number.MAX_SAFE_INTEGER, (this.amount_selected || 0) + step));
         }
     }
 });