diff --git a/changes/bug20261 b/changes/bug20261
new file mode 100644
index 0000000000..dfdd15924b
--- /dev/null
+++ b/changes/bug20261
@@ -0,0 +1,4 @@
+  o Minor bugfixes (client, unix domain sockets):
+    - Disable IsolateClientAddr when using AF_UNIX backed SocksPorts
+      as the client address is meaningless. Fixes bug 20261; bugfix on
+      0.2.6.3-alpha.
diff --git a/doc/tor.1.txt b/doc/tor.1.txt
index 2e73b2784c..330f0c1e32 100644
--- a/doc/tor.1.txt
+++ b/doc/tor.1.txt
@@ -1046,8 +1046,9 @@ The following options are useful only for clients (that is, if
     another.  Recognized isolation flags are:
     **IsolateClientAddr**;;
         Don't share circuits with streams from a different
-        client address.  (On by default and strongly recommended;
-        you can disable it with **NoIsolateClientAddr**.)
+        client address.  (On by default and strongly recommended when
+        supported; you can disable it with **NoIsolateClientAddr**.
+        Unsupported and force-disabled when using Unix domain sockets.)
     **IsolateSOCKSAuth**;;
         Don't share circuits with streams for which different
         SOCKS authentication was provided. (On by default;
diff --git a/src/or/config.c b/src/or/config.c
index 18cbe34be3..93e753bb49 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -6838,6 +6838,13 @@ parse_port_config(smartlist_t *out,
       goto err;
     }
 
+    if (unix_socket_path && (isolation & ISO_CLIENTADDR)) {
+      /* `IsolateClientAddr` is nonsensical in the context of AF_LOCAL.
+       * just silently remove the isolation flag.
+       */
+      isolation &= ~ISO_CLIENTADDR;
+    }
+
     if (out && port) {
       size_t namelen = unix_socket_path ? strlen(unix_socket_path) : 0;
       port_cfg_t *cfg = port_cfg_new(namelen);