diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
index 01bcbf1..57dfa2f 100644
--- a/Source/WebKit/ChangeLog
+++ b/Source/WebKit/ChangeLog
@@ -1,3 +1,31 @@
+2019-10-15  Wenson Hsieh  <wenson_hsieh@apple.com>
+
+        Fix the internal macOS build after r251171
+        https://bugs.webkit.org/show_bug.cgi?id=203022
+
+        Reviewed by Dan Bernstein.
+
+        Attempts to include <HIServices/AccessibilityPriv.h> in WebKit result in:
+
+        ```
+        fatal error: 'HIServices/AccessibilityPriv.h' file not found
+        ```
+
+        At least on macOS 10.15, it appears that HIServices.framework exists within the ApplicationServices framework.
+        To fix this build error, we can instead turn AccessibilityPrivSPI.h into an SPI header for ApplicationServices,
+        ApplicationServicesSPI.h, and use it in several places where we currently directly import <ApplicationServices/
+        ApplicationServicesPriv.h>.
+
+        * Platform/IPC/cocoa/ConnectionCocoa.mm:
+
+        Bring some more constants that were defined in the !USE(APPLE_INTERNAL_SDK) case into the ApplicationServices
+        SPI header.
+
+        * Platform/spi/mac/ApplicationServicesSPI.h: Renamed from Source/WebKit/Platform/spi/mac/AccessibilityPrivSPI.h.
+        * Shared/mac/AuxiliaryProcessMac.mm:
+        * WebKit.xcodeproj/project.pbxproj:
+        * WebProcess/WebPage/mac/WKAccessibilityWebPageObjectBase.mm:
+
 2019-10-15  Kate Cheney  <katherine_cheney@apple.com>
 
         REGRESSION (~244100) [Mac WK2 Debug] Layout Test http/tests/resourceLoadStatistics/prune-statistics.html is a flaky failure (197285)
diff --git a/Source/WebKit/Platform/IPC/cocoa/ConnectionCocoa.mm b/Source/WebKit/Platform/IPC/cocoa/ConnectionCocoa.mm
index 87dd28f..2391290 100644
--- a/Source/WebKit/Platform/IPC/cocoa/ConnectionCocoa.mm
+++ b/Source/WebKit/Platform/IPC/cocoa/ConnectionCocoa.mm
@@ -55,14 +55,7 @@
 
 #if PLATFORM(MAC)
 
-#if USE(APPLE_INTERNAL_SDK)
-#import <ApplicationServices/ApplicationServicesPriv.h>
-#else
-typedef enum {
-    AXSuspendStatusRunning = 0,
-    AXSuspendStatusSuspended,
-} AXSuspendStatus;
-#endif
+#import "ApplicationServicesSPI.h"
 
 extern "C" AXError _AXUIElementNotifyProcessSuspendStatus(AXSuspendStatus);
 
diff --git a/Source/WebKit/Platform/spi/mac/AccessibilityPrivSPI.h b/Source/WebKit/Platform/spi/mac/ApplicationServicesSPI.h
similarity index 90%
rename from Source/WebKit/Platform/spi/mac/AccessibilityPrivSPI.h
rename to Source/WebKit/Platform/spi/mac/ApplicationServicesSPI.h
index 784cda3..a31f2da 100644
--- a/Source/WebKit/Platform/spi/mac/AccessibilityPrivSPI.h
+++ b/Source/WebKit/Platform/spi/mac/ApplicationServicesSPI.h
@@ -25,16 +25,11 @@
 
 #pragma once
 
+#if PLATFORM(MAC)
+
 #if USE(APPLE_INTERNAL_SDK)
 
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wundef"
-
-#if PLATFORM(MAC)
-#include <HIServices/AccessibilityPriv.h>
-#endif
-
-#pragma clang diagnostic pop
+#import <ApplicationServices/ApplicationServicesPriv.h>
 
 #else
 
@@ -53,6 +48,13 @@
     kAXClientTypeDictation,
 };
 
+typedef enum {
+    AXSuspendStatusRunning = 0,
+    AXSuspendStatusSuspended,
+} AXSuspendStatus;
+
+#endif
+
 extern AXClientType _AXGetClientForCurrentRequestUntrusted(void);
 
-#endif // PLATFORM(APPLE_INTERNAL_SDK)
+#endif // PLATFORM(MAC)
diff --git a/Source/WebKit/Shared/mac/AuxiliaryProcessMac.mm b/Source/WebKit/Shared/mac/AuxiliaryProcessMac.mm
index 3675271..735e17e 100644
--- a/Source/WebKit/Shared/mac/AuxiliaryProcessMac.mm
+++ b/Source/WebKit/Shared/mac/AuxiliaryProcessMac.mm
@@ -28,6 +28,7 @@
 #if PLATFORM(MAC) || PLATFORM(MACCATALYST)
 #import "AuxiliaryProcess.h"
 
+#import "ApplicationServicesSPI.h"
 #import "CodeSigning.h"
 #import "QuarantineSPI.h"
 #import "SandboxInitializationParameters.h"
@@ -56,7 +57,6 @@
 #import <wtf/text/StringBuilder.h>
 
 #if USE(APPLE_INTERNAL_SDK)
-#import <ApplicationServices/ApplicationServicesPriv.h>
 #import <rootless.h>
 #endif
 
diff --git a/Source/WebKit/WebKit.xcodeproj/project.pbxproj b/Source/WebKit/WebKit.xcodeproj/project.pbxproj
index 84f96e6..f9952c1 100644
--- a/Source/WebKit/WebKit.xcodeproj/project.pbxproj
+++ b/Source/WebKit/WebKit.xcodeproj/project.pbxproj
@@ -1714,6 +1714,7 @@
 		F4D5F51D206087A10038BBA8 /* WKTextInputListViewController.h in Headers */ = {isa = PBXBuildFile; fileRef = F4D5F519206087A00038BBA8 /* WKTextInputListViewController.h */; };
 		F4D5F51F206087A10038BBA8 /* WKQuickboardListViewController.h in Headers */ = {isa = PBXBuildFile; fileRef = F4D5F51B206087A10038BBA8 /* WKQuickboardListViewController.h */; };
 		F4DB54E62319E733009E3155 /* WKHighlightLongPressGestureRecognizer.h in Headers */ = {isa = PBXBuildFile; fileRef = F4DB54E42319E733009E3155 /* WKHighlightLongPressGestureRecognizer.h */; };
+		F4EC94E32356CC57000BB614 /* ApplicationServicesSPI.h in Headers */ = {isa = PBXBuildFile; fileRef = 29D04E2821F7C73D0076741D /* ApplicationServicesSPI.h */; };
 		F6113E25126CE1820057D0A7 /* APIUserContentURLPattern.h in Headers */ = {isa = PBXBuildFile; fileRef = F6113E24126CE1820057D0A7 /* APIUserContentURLPattern.h */; };
 		F6113E29126CE19B0057D0A7 /* WKUserContentURLPattern.h in Headers */ = {isa = PBXBuildFile; fileRef = F6113E27126CE19B0057D0A7 /* WKUserContentURLPattern.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		F634445612A885C8000612D8 /* APISecurityOrigin.h in Headers */ = {isa = PBXBuildFile; fileRef = F634445512A885C8000612D8 /* APISecurityOrigin.h */; };
@@ -2548,7 +2549,7 @@
 		29AD3097164B4E210072DEA9 /* LegacyCustomProtocolManagerProxy.messages.in */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; name = LegacyCustomProtocolManagerProxy.messages.in; path = CustomProtocols/LegacyCustomProtocolManagerProxy.messages.in; sourceTree = "<group>"; };
 		29CD55A8128E294F00133C85 /* WKAccessibilityWebPageObjectBase.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = WKAccessibilityWebPageObjectBase.h; sourceTree = "<group>"; };
 		29CD55A9128E294F00133C85 /* WKAccessibilityWebPageObjectBase.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = WKAccessibilityWebPageObjectBase.mm; sourceTree = "<group>"; };
-		29D04E2821F7C73D0076741D /* AccessibilityPrivSPI.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = AccessibilityPrivSPI.h; sourceTree = "<group>"; };
+		29D04E2821F7C73D0076741D /* ApplicationServicesSPI.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = ApplicationServicesSPI.h; sourceTree = "<group>"; };
 		2D0035221BC7414800DA8716 /* PDFPlugin.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = PDFPlugin.h; path = PDF/PDFPlugin.h; sourceTree = "<group>"; };
 		2D0035231BC7414800DA8716 /* PDFPlugin.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = PDFPlugin.mm; path = PDF/PDFPlugin.mm; sourceTree = "<group>"; };
 		2D0C56FB229F1DEA00BD33E7 /* DeviceManagementSoftLink.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DeviceManagementSoftLink.h; sourceTree = "<group>"; };
@@ -7512,8 +7513,8 @@
 		A1E6886E1F6E2B82007006A6 /* mac */ = {
 			isa = PBXGroup;
 			children = (
-				29D04E2821F7C73D0076741D /* AccessibilityPrivSPI.h */,
 				F48D2A8421583A0200C6752B /* AppKitSPI.h */,
+				29D04E2821F7C73D0076741D /* ApplicationServicesSPI.h */,
 				A1E6886F1F6E2BAB007006A6 /* QuarantineSPI.h */,
 			);
 			path = mac;
@@ -9413,6 +9414,7 @@
 				1AE286841C7F93860069AC4F /* APIWebsiteDataRecord.h in Headers */,
 				1A6563E51B7A8C50009CF787 /* APIWindowFeatures.h in Headers */,
 				F48D2A8521583A7E00C6752B /* AppKitSPI.h in Headers */,
+				F4EC94E32356CC57000BB614 /* ApplicationServicesSPI.h in Headers */,
 				1AD4C1931B39F33200ABC28E /* ApplicationStateTracker.h in Headers */,
 				1AEFD27911D16C81008219D3 /* ArgumentCoder.h in Headers */,
 				1AEFD2F711D1807B008219D3 /* ArgumentCoders.h in Headers */,
diff --git a/Source/WebKit/WebProcess/WebPage/mac/WKAccessibilityWebPageObjectBase.mm b/Source/WebKit/WebProcess/WebPage/mac/WKAccessibilityWebPageObjectBase.mm
index d0d5657..53fcb84 100644
--- a/Source/WebKit/WebProcess/WebPage/mac/WKAccessibilityWebPageObjectBase.mm
+++ b/Source/WebKit/WebProcess/WebPage/mac/WKAccessibilityWebPageObjectBase.mm
@@ -26,7 +26,7 @@
 #import "config.h"
 #import "WKAccessibilityWebPageObjectBase.h"
 
-#import "AccessibilityPrivSPI.h"
+#import "ApplicationServicesSPI.h"
 #import "WebFrame.h"
 #import "WebPage.h"
 #import "WKArray.h"