diff --git a/django/contrib/admin/static/admin/css/changelists.css b/django/contrib/admin/static/admin/css/changelists.css
index f9adf0c085b..b4a1557887a 100644
--- a/django/contrib/admin/static/admin/css/changelists.css
+++ b/django/contrib/admin/static/admin/css/changelists.css
@@ -128,8 +128,8 @@
 /* FILTER COLUMN */
 
 #changelist-filter {
+    flex: 0 0 240px;
     order: 1;
-    width: 240px;
     background: var(--darkened-bg);
     border-left: none;
     margin: 0 0 0 30px;
diff --git a/django/contrib/admin/static/admin/css/responsive.css b/django/contrib/admin/static/admin/css/responsive.css
index e60a6f02c7e..8c6dd810ca2 100644
--- a/django/contrib/admin/static/admin/css/responsive.css
+++ b/django/contrib/admin/static/admin/css/responsive.css
@@ -157,7 +157,7 @@ input[type="submit"], button {
     }
 
     #changelist-filter {
-        width: 200px;
+        flex-basis: 200px;
     }
 
     .change-list .filtered .results,
diff --git a/docs/releases/3.1.6.txt b/docs/releases/3.1.6.txt
index dfc60acc95a..2d0a48616dc 100644
--- a/docs/releases/3.1.6.txt
+++ b/docs/releases/3.1.6.txt
@@ -9,4 +9,5 @@ Django 3.1.6 fixes several bugs in 3.1.5.
 Bugfixes
 ========
 
-* ...
+* Fixed an admin layout issue in Django 3.1 where changelist filter controls 
+  would become squashed (:ticket:`32391`).