diff --git a/src/MacVim/MMAppController.m b/src/MacVim/MMAppController.m
index 7cb7b887f4..8eadcf13c3 100644
--- a/src/MacVim/MMAppController.m
+++ b/src/MacVim/MMAppController.m
@@ -481,13 +481,11 @@ fsEventCallback(ConstFSEventStreamRef streamRef,
     int reply = NSTerminateNow;
     BOOL modifiedBuffers = NO;
 
-    // Go through windows, checking for modified buffers.  (Each Vim process
-    // tells MacVim when any buffer has been modified and MacVim sets the
-    // 'documentEdited' flag of the window correspondingly.)
-    NSEnumerator *e = [[NSApp windows] objectEnumerator];
-    id window;
-    while ((window = [e nextObject])) {
-        if ([window isDocumentEdited]) {
+    // Go through Vim controllers, checking for modified buffers.
+    NSEnumerator *e = [vimControllers objectEnumerator];
+    id vc;
+    while ((vc = [e nextObject])) {
+        if ([vc hasModifiedBuffer]) {
             modifiedBuffers = YES;
             break;
         }
@@ -519,7 +517,6 @@ fsEventCallback(ConstFSEventStreamRef streamRef,
 
         // Count the number of open tabs
         e = [vimControllers objectEnumerator];
-        id vc;
         while ((vc = [e nextObject]))
             numTabs += [[vc objectForVimStateKey:@"numTabs"] intValue];
 
diff --git a/src/MacVim/MMBackend.m b/src/MacVim/MMBackend.m
index 92d6899367..2d389c14e5 100644
--- a/src/MacVim/MMBackend.m
+++ b/src/MacVim/MMBackend.m
@@ -191,7 +191,7 @@ extern GuiFont gui_mch_retain_font(GuiFont font);
 - (void)startOdbEditWithArguments:(NSDictionary *)args;
 - (void)handleXcodeMod:(NSData *)data;
 - (void)handleOpenWithArguments:(NSDictionary *)args;
-- (BOOL)checkForModifiedBuffers;
+- (int)checkForModifiedBuffers;
 - (void)addInput:(NSString *)input;
 - (void)redrawScreen;
 - (void)handleFindReplace:(NSDictionary *)args;
@@ -1182,12 +1182,10 @@ extern GuiFont gui_mch_retain_font(GuiFont font);
 
 - (void)updateModifiedFlag
 {
-    // Notify MacVim if _any_ buffer has changed from unmodified to modified or
-    // vice versa.
-    int msgid = [self checkForModifiedBuffers]
-            ? BuffersModifiedMsgID : BuffersNotModifiedMsgID;
-
-    [self queueMessage:msgid data:nil];
+    int state = [self checkForModifiedBuffers];
+    NSMutableData *data = [NSMutableData data];
+    [data appendBytes:&state length:sizeof(int)];
+    [self queueMessage:SetBuffersModifiedMsgID data:data];
 }
 
 - (oneway void)processInput:(int)msgid data:(in bycopy NSData *)data
@@ -1818,6 +1816,8 @@ static void netbeansReadCallback(CFSocketRef s,
         nil];
 
     // Put the state before all other messages.
+    // TODO: If called multiple times the oldest state will be used! Should
+    // remove any current Vim state messages from the queue first.
     int msgid = SetVimStateMsgID;
     [outputQueue insertObject:[vimState dictionaryAsData] atIndex:0];
     [outputQueue insertObject:[NSData dataWithBytes:&msgid length:sizeof(int)]
@@ -2836,16 +2836,22 @@ static void netbeansReadCallback(CFSocketRef s,
     }
 }
 
-- (BOOL)checkForModifiedBuffers
+- (int)checkForModifiedBuffers
 {
+    // Return 1 if current buffer is modified, -1 if other buffer is modified,
+    // otherwise return 0.
+
+    if (curbuf && bufIsChanged(curbuf))
+        return 1;
+
     buf_T *buf;
     for (buf = firstbuf; buf != NULL; buf = buf->b_next) {
         if (bufIsChanged(buf)) {
-            return YES;
+            return -1;
         }
     }
 
-    return NO;
+    return 0;
 }
 
 - (void)addInput:(NSString *)input
diff --git a/src/MacVim/MMVimController.h b/src/MacVim/MMVimController.h
index b9fbaac0c5..7246e68460 100644
--- a/src/MacVim/MMVimController.h
+++ b/src/MacVim/MMVimController.h
@@ -34,6 +34,7 @@
     NSDictionary        *vimState;
     BOOL                isPreloading;
     NSDate              *creationDate;
+    BOOL                hasModifiedBuffer;
 }
 
 - (id)initWithBackend:(id)backend pid:(int)processIdentifier;
@@ -48,6 +49,7 @@
 - (NSMenu *)mainMenu;
 - (BOOL)isPreloading;
 - (void)setIsPreloading:(BOOL)yn;
+- (BOOL)hasModifiedBuffer;
 - (NSDate *)creationDate;
 - (void)cleanup;
 - (void)dropFiles:(NSArray *)filenames forceOpen:(BOOL)force;
diff --git a/src/MacVim/MMVimController.m b/src/MacVim/MMVimController.m
index d56745df6d..897843848a 100644
--- a/src/MacVim/MMVimController.m
+++ b/src/MacVim/MMVimController.m
@@ -220,6 +220,11 @@ static BOOL isUnsafeMessage(int msgid);
     isPreloading = yn;
 }
 
+- (BOOL)hasModifiedBuffer
+{
+    return hasModifiedBuffer;
+}
+
 - (NSDate *)creationDate
 {
     return creationDate;
@@ -765,10 +770,21 @@ static BOOL isUnsafeMessage(int msgid);
         [windowController enterFullscreen:fuoptions backgroundColor:back];
     } else if (LeaveFullscreenMsgID == msgid) {
         [windowController leaveFullscreen];
-    } else if (BuffersNotModifiedMsgID == msgid) {
-        [windowController setBuffersModified:NO];
-    } else if (BuffersModifiedMsgID == msgid) {
-        [windowController setBuffersModified:YES];
+    } else if (SetBuffersModifiedMsgID == msgid) {
+        const void *bytes = [data bytes];
+        // state < 0  <->  some buffer modified
+        // state > 0  <->  current buffer modified
+        int state = *((int*)bytes); bytes += sizeof(int);
+
+        // NOTE: The window controller tracks whether current buffer is
+        // modified or not (and greys out the proxy icon as well as putting a
+        // dot in the red "close button" if necessary).  The Vim controller
+        // tracks whether any buffer has been modified (used to decide whether
+        // to show a warning or not when quitting).
+        //
+        // TODO: Make 'hasModifiedBuffer' part of the Vim state?
+        [windowController setBufferModified:(state > 0)];
+        hasModifiedBuffer = (state != 0);
     } else if (SetPreEditPositionMsgID == msgid) {
         const int *dim = (const int*)[data bytes];
         [[[windowController vimView] textView] setPreEditRow:dim[0]
diff --git a/src/MacVim/MMWindowController.h b/src/MacVim/MMWindowController.h
index 12084520c0..99884c4e40 100644
--- a/src/MacVim/MMWindowController.h
+++ b/src/MacVim/MMWindowController.h
@@ -79,7 +79,7 @@
 - (void)leaveFullscreen;
 - (void)setFullscreenBackgroundColor:(NSColor *)back;
 
-- (void)setBuffersModified:(BOOL)mod;
+- (void)setBufferModified:(BOOL)mod;
 - (void)setTopLeft:(NSPoint)pt;
 - (BOOL)getDefaultTopLeft:(NSPoint*)pt;
 
diff --git a/src/MacVim/MMWindowController.m b/src/MacVim/MMWindowController.m
index a6e2ffea9a..f367145551 100644
--- a/src/MacVim/MMWindowController.m
+++ b/src/MacVim/MMWindowController.m
@@ -670,7 +670,7 @@
         [fullscreenWindow setBackgroundColor:back];
 }
 
-- (void)setBuffersModified:(BOOL)mod
+- (void)setBufferModified:(BOOL)mod
 {
     // NOTE: We only set the document edited flag on the decorated window since
     // the full-screen window has no close button anyway.  (It also saves us
diff --git a/src/MacVim/MacVim.h b/src/MacVim/MacVim.h
index 26b5af775e..20ff1a6a9d 100644
--- a/src/MacVim/MacVim.h
+++ b/src/MacVim/MacVim.h
@@ -158,8 +158,7 @@ enum {
     SetServerNameMsgID,
     EnterFullscreenMsgID,
     LeaveFullscreenMsgID,
-    BuffersNotModifiedMsgID,
-    BuffersModifiedMsgID,
+    SetBuffersModifiedMsgID,
     AddInputMsgID,
     SetPreEditPositionMsgID,
     TerminateNowMsgID,
diff --git a/src/MacVim/MacVim.m b/src/MacVim/MacVim.m
index 2b10c8bfed..25f5776c6c 100644
--- a/src/MacVim/MacVim.m
+++ b/src/MacVim/MacVim.m
@@ -68,8 +68,7 @@ char *MessageStrings[] =
     "SetServerNameMsgID",
     "EnterFullscreenMsgID",
     "LeaveFullscreenMsgID",
-    "BuffersNotModifiedMsgID",
-    "BuffersModifiedMsgID",
+    "SetBuffersModifiedMsgID",
     "AddInputMsgID",
     "SetPreEditPositionMsgID",
     "TerminateNowMsgID",