diff --git a/src/mozc_version_template.txt b/src/mozc_version_template.txt
index 9cd8f9b13..322f5496b 100644
--- a/src/mozc_version_template.txt
+++ b/src/mozc_version_template.txt
@@ -1,6 +1,6 @@
 MAJOR=2
 MINOR=17
-BUILD=2107
+BUILD=2108
 REVISION=102
 # NACL_DICTIONARY_VERSION is the target version of the system dictionary to be
 # downloaded by NaCl Mozc.
diff --git a/src/unix/ibus/mozc_engine.cc b/src/unix/ibus/mozc_engine.cc
index 602352d24..71c528b1f 100644
--- a/src/unix/ibus/mozc_engine.cc
+++ b/src/unix/ibus/mozc_engine.cc
@@ -716,14 +716,12 @@ bool MozcEngine::ExecuteCallback(IBusEngine *engine,
 
   switch (callback_command.type()) {
     case commands::SessionCommand::UNDO:
-      // As far as I've tested on Ubuntu 11.10, most of applications which
-      // accept 'ibus_engine_delete_surrounding_text' doe not set
-      // IBUS_CAP_SURROUNDING_TEXT bit.
-      // So we should carefully uncomment the following code.
-      // -----
-      // if (!(engine->client_capabilities & IBUS_CAP_SURROUNDING_TEXT)) {
-      //   return false;
-      // }
+      // Having |IBUS_CAP_SURROUNDING_TEXT| does not necessarily mean that the
+      // client supports |ibus_engine_delete_surrounding_text()|, but there is
+      // no other good criteria.
+      if (!(engine->client_capabilities & IBUS_CAP_SURROUNDING_TEXT)) {
+        return false;
+      }
       break;
     case commands::SessionCommand::CONVERT_REVERSE: {
       if (!GetSurroundingText(engine,