diff --git a/Source/WebKit2/ChangeLog b/Source/WebKit2/ChangeLog
index a87639fe245ae395224576ac43001e654e0ee974..7af40045490538aecb23fafa402425d09fa00552 100644
--- a/Source/WebKit2/ChangeLog
+++ b/Source/WebKit2/ChangeLog
@@ -1,3 +1,18 @@
+2012-01-06  Alexey Proskuryakov  <ap@apple.com>
+
+        [Mac] Thread verifier assertions when printing
+        https://bugs.webkit.org/show_bug.cgi?id=75738
+
+        Reviewed by Sam Weinig.
+
+        * UIProcess/API/mac/WKPrintingView.mm:
+        (-[WKPrintingView dealloc]): Dealloc in main thread, so that WebFrameProxy doesn't get
+        deref'ed from a secondary one.
+        (-[WKPrintingView _adjustPrintingMarginsForHeaderAndFooter]): This method calls out to client,
+        which only expects that on main thread.
+        (-[WKPrintingView knowsPageRange:]): Call _adjustPrintingMarginsForHeaderAndFooter on main
+        thread.
+
 2012-01-06  Alexey Proskuryakov  <ap@apple.com>
 
         Need to allow SCNetworkReachability service in sandbox profile
diff --git a/Source/WebKit2/UIProcess/API/mac/WKPrintingView.mm b/Source/WebKit2/UIProcess/API/mac/WKPrintingView.mm
index 14fe79add21d93c95b95a51fc6bfc246ea638acc..5ab899f5f31dac8ebd955718e99ee39e8de442bd 100644
--- a/Source/WebKit2/UIProcess/API/mac/WKPrintingView.mm
+++ b/Source/WebKit2/UIProcess/API/mac/WKPrintingView.mm
@@ -30,6 +30,7 @@
 #import "PrintInfo.h"
 #import "WebData.h"
 #import "WebPageProxy.h"
+#import <WebCore/WebCoreObjCExtras.h>
 #import <wtf/MainThread.h>
 
 using namespace WebKit;
@@ -56,6 +57,14 @@ static BOOL isForcingPreviewUpdate;
     return self;
 }
 
+- (void)dealloc
+{
+    if (WebCoreObjCScheduleDeallocateOnMainThread([WKPrintingView class], self))
+        return;
+
+    [super dealloc];
+}
+
 - (BOOL)isFlipped
 {
     return YES;
@@ -110,6 +119,8 @@ static BOOL isForcingPreviewUpdate;
 
 - (void)_adjustPrintingMarginsForHeaderAndFooter
 {
+    ASSERT(isMainThread()); // This funciton calls the client, which should only be done on main thread.
+
     NSPrintInfo *info = [_printOperation printInfo];
     NSMutableDictionary *infoDictionary = [info dictionary];
 
@@ -364,7 +375,7 @@ static void prepareDataForPrintingOnSecondaryThread(void* untypedContext)
 
     [self _suspendAutodisplay];
     
-    [self _adjustPrintingMarginsForHeaderAndFooter];
+    [self performSelectorOnMainThread:@selector(_adjustPrintingMarginsForHeaderAndFooter) withObject:nil waitUntilDone:YES];
 
     if ([self _hasPageRects])
         *range = NSMakeRange(1, _printingPageRects.size());