diff --git a/delegateuitask_darwin.m b/delegateuitask_darwin.m
index a49fda3..023cb49 100644
--- a/delegateuitask_darwin.m
+++ b/delegateuitask_darwin.m
@@ -9,6 +9,7 @@
 // see the hack below; we'll include everything first just in case some other headers get included below; if the hack ever gets resolved, we can use the ones below instead
 #import <Foundation/NSAutoreleasePool.h>
 #import <AppKit/NSEvent.h>
+#import <AppKit/NSAlert.h>
 
 // HACK.
 // Apple's header files are bugged: there's an enum that was introduced in 10.7 with new values added in 10.8, but instead of wrapping the whole enum in a version check, they wrap just the fields. This means that on 10.6 that enum will be empty, which is illegal.
@@ -33,6 +34,7 @@
 #import <AppKit/NSWindow.h>
 #import <Foundation/NSAutoreleasePool.h>
 #import <AppKit/NSEvent.h>
+#import <AppKit/NSAlert.h>
 
 extern NSRect dummyRect;
 
@@ -68,6 +70,10 @@ extern NSRect dummyRect;
 	return NSTerminateCancel;
 }
 
+- (void)alertDidEnd:(NSAlert *)alert returnCode:(NSInteger)returnCode contextInfo:(void *)contextInfo
+{
+}
+
 @end
 
 id makeAppDelegate(void)
diff --git a/dialog_darwin.go b/dialog_darwin.go
index 81819ba..ef1cd6c 100644
--- a/dialog_darwin.go
+++ b/dialog_darwin.go
@@ -9,10 +9,15 @@ import (
 // #include "objc_darwin.h"
 import "C"
 
-func _msgBox(primarytext string, secondarytext string, style uintptr) {
+func _msgBox(parent *Window, primarytext string, secondarytext string, style uintptr) {
 	ret := make(chan struct{})
 	defer close(ret)
 	uitask <- func() {
+		var pwin C.id = nil
+
+		if parent != nil {
+			pwin = parent.sysData.id
+		}
 		primary := toNSString(primarytext)
 		secondary := C.id(nil)
 		if secondarytext != "" {
@@ -20,19 +25,19 @@ func _msgBox(primarytext string, secondarytext string, style uintptr) {
 		}
 		switch style {
 		case 0:		// normal
-			C.msgBox(primary, secondary)
+			C.msgBox(pwin, primary, secondary)
 		case 1:		// error
-			C.msgBoxError(primary, secondary)
+			C.msgBoxError(pwin, primary, secondary)
 		}
 		ret <- struct{}{}
 	}
 	<-ret
 }
 
-func msgBox(primarytext string, secondarytext string) {
-	_msgBox(primarytext, secondarytext, 0)
+func msgBox(parent *Window, primarytext string, secondarytext string) {
+	_msgBox(parent, primarytext, secondarytext, 0)
 }
 
-func msgBoxError(primarytext string, secondarytext string) {
-	_msgBox(primarytext, secondarytext, 1)
+func msgBoxError(parent *Window, primarytext string, secondarytext string) {
+	_msgBox(parent, primarytext, secondarytext, 1)
 }
diff --git a/dialog_darwin.m b/dialog_darwin.m
index b147c5a..6bbad61 100644
--- a/dialog_darwin.m
+++ b/dialog_darwin.m
@@ -3,7 +3,27 @@
 #include "objc_darwin.h"
 #import <AppKit/NSAlert.h>
 
-static void alert(NSString *primary, NSString *secondary, NSAlertStyle style)
+// see delegateuitask_darwin.m
+// in this case, NSWindow.h includes NSApplication.h
+
+#ifdef MAC_OS_X_VERSION_10_7
+#undef MAC_OS_X_VERSION_MIN_REQUIRED
+#undef MAC_OS_X_VERSION_MAX_ALLOWED
+#define MAC_OS_X_VERSION_MIN_REQUIRED MAC_OS_X_VERSION_10_7
+#define MAC_OS_X_VERSION_MAX_ALLOWED MAC_OS_X_VERSION_10_7
+#endif
+#import <AppKit/NSApplication.h>
+#undef MAC_OS_X_VERSION_MIN_REQUIRED
+#undef MAC_OS_X_VERSION_MAX_ALLOWED
+#define MAC_OS_X_VERSION_MIN_REQUIRED MAC_OS_X_VERSION_10_6
+#define MAC_OS_X_VERSION_MAX_ALLOWED MAC_OS_X_VERSION_10_6
+
+#import <AppKit/NSWindow.h>
+
+#define to(T, x) ((T *) (x))
+#define toNSWindow(x) to(NSWindow, (x))
+
+static void alert(id parent, NSString *primary, NSString *secondary, NSAlertStyle style)
 {
 	NSAlert *box;
 
@@ -14,15 +34,21 @@ static void alert(NSString *primary, NSString *secondary, NSAlertStyle style)
 	[box setAlertStyle:style];
 	// TODO is there a named constant? will also need to be changed when we add different dialog types
 	[box addButtonWithTitle:@"OK"];
-	[box runModal];
+	if (parent == nil)
+		[box runModal];
+	else
+		[box beginSheetModalForWindow:toNSWindow(parent)
+			modalDelegate:[NSApp delegate]
+			didEndSelector:@selector(alertDidEnd:returnCode:contextInfo:)
+			contextInfo:NULL];
 }
 
-void msgBox(id primary, id secondary)
+void msgBox(id parent, id primary, id secondary)
 {
-	alert((NSString *) primary, (NSString *) secondary, NSInformationalAlertStyle);
+	alert(parent, (NSString *) primary, (NSString *) secondary, NSInformationalAlertStyle);
 }
 
-void msgBoxError(id primary, id secondary)
+void msgBoxError(id parent, id primary, id secondary)
 {
-	alert((NSString *) primary, (NSString *) secondary, NSCriticalAlertStyle);
+	alert(parent, (NSString *) primary, (NSString *) secondary, NSCriticalAlertStyle);
 }
diff --git a/objc_darwin.h b/objc_darwin.h
index e26db6f..fd2058a 100644
--- a/objc_darwin.h
+++ b/objc_darwin.h
@@ -61,8 +61,8 @@ extern void breakMainLoop(void);
 extern void cocoaMainLoop(void);
 
 /* dialog_darwin.m */
-extern void msgBox(id, id);
-extern void msgBoxError(id, id);
+extern void msgBox(id, id, id);
+extern void msgBoxError(id, id, id);
 
 /* listbox_darwin.m */
 extern id toListboxItem(id, id);