diff --git a/Source/InputMethodController.mm b/Source/InputMethodController.mm
index 54417f6f..9cce3627 100644
--- a/Source/InputMethodController.mm
+++ b/Source/InputMethodController.mm
@@ -243,7 +243,7 @@ static inline NSString *LocalizationNotNeeded(NSString *s) {
     BOOL result = [_keyHandler handleInput:input state:_state stateCallback:^(InputState *state) {
         [self handleState:state client:client];
     }           candidateSelectionCallback:^{
-//        NSLog(@"candidate window updated.");
+        NSLog(@"candidate window updated.");
     }                        errorCallback:^{
         NSBeep();
     }];
@@ -295,7 +295,7 @@ static inline NSString *LocalizationNotNeeded(NSString *s) {
 
 - (void)handleState:(InputState *)newState client:(id)client
 {
-//    NSLog(@"current state: %@ new state: %@", _state, newState );
+    NSLog(@"new state: %@ / current state: %@", newState, _state);
 
     // We need to set the state to the member variable since the candidate
     // window need to read the candidates from it.
@@ -408,15 +408,8 @@ static inline NSString *LocalizationNotNeeded(NSString *s) {
     // i.e. the client app needs to take care of where to put ths composing buffer
     [client setMarkedText:attrString selectionRange:NSMakeRange(cursorIndex, 0) replacementRange:NSMakeRange(NSNotFound, NSNotFound)];
 
-    if (_keyHandler.inputMode == kPlainBopomofoModeIdentifier && state.candidates.count == 1) {
-        NSString *buffer = [self _convertToSimplifiedChineseIfRequired:state.candidates.firstObject];
-        [client insertText:buffer replacementRange:NSMakeRange(NSNotFound, NSNotFound)];
-        InputStateEmpty *empty = [[InputStateEmpty alloc] init];
-        [self handleState:empty client:client];
-    } else {
-        if (![previous isKindOfClass:[InputStateChoosingCandidate class]]) {
-            [self _showCandidateWindowWithState:state client:client];
-        }
+    if (![previous isKindOfClass:[InputStateChoosingCandidate class]]) {
+        [self _showCandidateWindowWithState:state client:client];
     }
 }
 
diff --git a/Source/KeyHandler.mm b/Source/KeyHandler.mm
index 5ee9135d..a9002333 100644
--- a/Source/KeyHandler.mm
+++ b/Source/KeyHandler.mm
@@ -343,7 +343,15 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
 
         if (_inputMode == kPlainBopomofoModeIdentifier) {
             InputStateChoosingCandidate *choosingCandidates = [self _buildCandidateState:inputting useVerticalMode:input.useVerticalMode];
-            stateCallback(choosingCandidates);
+            if (choosingCandidates.candidates.count == 1) {
+                [self clear];
+                InputStateCommitting *committing = [[InputStateCommitting alloc] initWithPoppedText:choosingCandidates.candidates.firstObject];
+                stateCallback(committing);
+                InputStateEmpty *empty = [[InputStateEmpty alloc] init];
+                stateCallback(empty);
+            } else {
+                stateCallback(choosingCandidates);
+            }
         }
 
         // and tells the client that the key is consumed
@@ -699,13 +707,20 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
 - (BOOL)_handleEnterWithState:(InputState *)state stateCallback:(void (^)(InputState *))stateCallback errorCallback:(void (^)(void))errorCallback
 {
     if ([state isKindOfClass:[InputStateInputting class]]) {
+        if (_inputMode == kPlainBopomofoModeIdentifier) {
+            if (!_bpmfReadingBuffer->isEmpty()) {
+                errorCallback();
+            }
+            return YES;
+        }
+
         [self clear];
 
         InputStateInputting *current = (InputStateInputting *) state;
         NSString *composingBuffer = current.composingBuffer;
         InputStateCommitting *committing = [[InputStateCommitting alloc] initWithPoppedText:composingBuffer];
         stateCallback(committing);
-        InputState *empty = [[InputState alloc] init];
+        InputStateEmpty *empty = [[InputStateEmpty alloc] init];
         stateCallback(empty);
         return YES;
     }
@@ -991,7 +1006,8 @@ static NSString *const kGraphVizOutputfile = @"/tmp/McBopomofo-visualization.dot
             if (candidateIndex != NSUIntegerMax) {
                 [self.delegate keyHandler:self didSelectCandidateAtIndex:candidateIndex candidateController:gCurrentCandidateController];
                 [self clear];
-                InputStateEmpty *empty = [[InputStateEmpty alloc] init];
+                InputStateEmptyIgnoringPreviousState *empty = [[InputStateEmptyIgnoringPreviousState alloc] init];
+                stateCallback(empty);
                 [self handleInput:input state:empty stateCallback:stateCallback candidateSelectionCallback:candidateSelectionCallback errorCallback:errorCallback];
             }
             return YES;