diff --git a/adb/adb.c b/adb/adb.c
index 1bf4b9e..a3cd281 100644
--- a/adb/adb.c
+++ b/adb/adb.c
@@ -402,6 +402,8 @@
         return "device";
     case CS_OFFLINE:
         return "offline";
+    case CS_UNAUTHORIZED:
+        return "unauthorized";
     default:
         return "unknown";
     }
@@ -531,6 +533,7 @@
 
     case A_AUTH:
         if (p->msg.arg0 == ADB_AUTH_TOKEN) {
+            t->connection_state = CS_UNAUTHORIZED;
             t->key = adb_auth_nextkey(t->key);
             if (t->key) {
                 send_auth_response(p->data, p->msg.data_length, t);
diff --git a/adb/adb.h b/adb/adb.h
index 9da8af8..a01d460 100644
--- a/adb/adb.h
+++ b/adb/adb.h
@@ -468,6 +468,7 @@
 #define CS_RECOVERY   4
 #define CS_NOPERM     5 /* Insufficient permissions to communicate with the device */
 #define CS_SIDELOAD   6
+#define CS_UNAUTHORIZED 7
 
 extern int HOST;
 extern int SHELL_EXIT_NOTIFY_FD;
diff --git a/adb/transport.c b/adb/transport.c
index 9fd6cc2..b4abb66 100644
--- a/adb/transport.c
+++ b/adb/transport.c
@@ -851,6 +851,12 @@
     adb_mutex_unlock(&transport_lock);
 
     if (result) {
+        if (result->connection_state == CS_UNAUTHORIZED) {
+            if (error_out)
+                *error_out = "device unauthorized. Please check the confirmation dialog on your device.";
+            result = NULL;
+        }
+
          /* offline devices are ignored -- they are either being born or dying */
         if (result && result->connection_state == CS_OFFLINE) {
             if (error_out)
@@ -888,6 +894,7 @@
     case CS_RECOVERY: return "recovery";
     case CS_SIDELOAD: return "sideload";
     case CS_NOPERM: return "no permissions";
+    case CS_UNAUTHORIZED: return "unauthorized";
     default: return "unknown";
     }
 }