diff --git a/XVim/XVimKeyStroke.h b/XVim/XVimKeyStroke.h
index 33d1788e..a7864ba2 100644
--- a/XVim/XVimKeyStroke.h
+++ b/XVim/XVimKeyStroke.h
@@ -29,6 +29,7 @@ NSString* XVimKeyNotationFromXVimString(XVimString* string);
 @property unsigned char modifier;
 @property (nonatomic, readonly) BOOL isNumeric;
 @property (nonatomic, readonly) BOOL isPrintable;
+@property (nonatomic, readonly) BOOL isWhitespace;
 
 - (id)initWithCharacter:(unichar)c modifier:(unsigned char)mod;
 
diff --git a/XVim/XVimKeyStroke.m b/XVim/XVimKeyStroke.m
index d0981e37..ee63d9f3 100644
--- a/XVim/XVimKeyStroke.m
+++ b/XVim/XVimKeyStroke.m
@@ -322,6 +322,13 @@ NS_INLINE BOOL isPrintable(unichar c)
     return !isNSFunctionKey(c) && iswprint_l(c, s_locale);
 }
 
+NS_INLINE BOOL isWhitespace(unichar c)
+{
+    init_maps();
+
+    return !isNSFunctionKey(c) && iswspace_l(c, s_locale);
+}
+
 NS_INLINE BOOL isValidKey(NSString *key)
 {
     init_maps();
@@ -619,6 +626,11 @@ - (BOOL)isPrintable
     return !_modifier && isPrintable(_character);
 }
 
+- (BOOL)isWhitespace
+{
+    return !_modifier && isWhitespace(_character);
+}
+
 - (NSString*)keyNotation{
     NSMutableString *keyStr = [[NSMutableString alloc] init];
     unichar charcode = _character;
diff --git a/XVim/XVimReplaceEvaluator.m b/XVim/XVimReplaceEvaluator.m
index a5564a12..269ca338 100644
--- a/XVim/XVimReplaceEvaluator.m
+++ b/XVim/XVimReplaceEvaluator.m
@@ -90,8 +90,8 @@ - (XVimEvaluator*)eval:(XVimKeyStroke*)keyStroke{
             // Here we pass the key input to original text view.
             // The input coming to this method is already handled by "Input Method"
             // and the input maight be non ascii like 'あ'
-            if (self.oneCharMode || keyStroke.isPrintable) {
-                if (!keyStroke.isPrintable) {
+            if (self.oneCharMode || keyStroke.isPrintable || keyStroke.isWhitespace) {
+                if (!keyStroke.isPrintable && !keyStroke.isWhitespace) {
                     nextEvaluator = [XVimEvaluator invalidEvaluator];
                 } else if (![self.sourceView xvim_replaceCharacters:keyStroke.character count:1]) {
                     nextEvaluator = [XVimEvaluator invalidEvaluator];