diff --git a/Mac/BuildScript/build-installer.py b/Mac/BuildScript/build-installer.py
index 69f3ff7ee90..0859b3aa068 100755
--- a/Mac/BuildScript/build-installer.py
+++ b/Mac/BuildScript/build-installer.py
@@ -215,6 +215,9 @@ def library_recipes():
               name="Tk 8.5.15",
               url="ftp://ftp.tcl.tk/pub/tcl//tcl8_5/tk8.5.15-src.tar.gz",
               checksum='55b8e33f903210a4e1c8bce0f820657f',
+              patches=[
+                  "issue19373_tk_8_5_15_source.patch",
+                   ],
               buildDir="unix",
               configure_pre=[
                     '--enable-aqua',
@@ -797,8 +800,6 @@ def buildRecipe(recipe, basedir, archList):
 
     workDir = extractArchive(buildDir, sourceArchive)
     os.chdir(workDir)
-    if 'buildDir' in recipe:
-        os.chdir(recipe['buildDir'])
 
     for patch in recipe.get('patches', ()):
         if isinstance(patch, tuple):
@@ -825,6 +826,9 @@ def buildRecipe(recipe, basedir, archList):
         runCommand('sh %s' % shellQuote(fn))
         os.unlink(fn)
 
+    if 'buildDir' in recipe:
+        os.chdir(recipe['buildDir'])
+
     if configure is not None:
         configure_args = [
             "--prefix=/usr/local",
diff --git a/Mac/BuildScript/issue19373_tk_8_5_15_source.patch b/Mac/BuildScript/issue19373_tk_8_5_15_source.patch
new file mode 100644
index 00000000000..de5d08e9d6c
--- /dev/null
+++ b/Mac/BuildScript/issue19373_tk_8_5_15_source.patch
@@ -0,0 +1,13 @@
+Issue #19373: Patch to Tk 8.5.15 to correct refresh problem on OS x 10.9.
+From upstream checkin https://core.tcl.tk/tk/info/5a5abf71f9
+
+--- tk8.5.15/macosx/tkMacOSXDraw.c	2013-09-16 09:41:21.000000000 -0700
++++ Tk_Source_Code-5a5abf71f9fdb0da/macosx/tkMacOSXDraw.c	2013-10-27 13:27:00.000000000 -0700
+@@ -1688,6 +1688,7 @@
+ {
+     if (dcPtr->context) {
+ 	CGContextSynchronize(dcPtr->context);
++	[[dcPtr->view window] setViewsNeedDisplay:YES];
+ 	[[dcPtr->view window] enableFlushWindow];
+ 	if (dcPtr->focusLocked) {
+ 	    [dcPtr->view unlockFocus];