diff --git a/browser/app/Makefile.in b/browser/app/Makefile.in
index 5411f943749..090444e4769 100644
--- a/browser/app/Makefile.in
+++ b/browser/app/Makefile.in
@@ -92,6 +92,9 @@ endif
 
 ifeq ($(OS_ARCH),WINNT)
 RCINCLUDE = splash.rc
+# Rebuild firefox.exe if the manifest changes - it's included by splash.rc.
+# (this dependency should really be just for firefox.exe, not other targets)
+EXTRA_DEPS += $(PROGRAM).manifest
 ifndef GNU_CC
 RCFLAGS += -DMOZ_PHOENIX -I$(srcdir)
 else
diff --git a/browser/app/firefox.exe.manifest b/browser/app/firefox.exe.manifest
index 87d53058c9e..b5a6cc7c4bc 100644
--- a/browser/app/firefox.exe.manifest
+++ b/browser/app/firefox.exe.manifest
@@ -26,6 +26,11 @@
     </ms_asmv3:requestedPrivileges>
   </ms_asmv3:security>
 </ms_asmv3:trustInfo>
+  <ms_asmv3:application xmlns:ms_asmv3="urn:schemas-microsoft-com:asm.v3">
+    <ms_asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">
+      <dpiAware>true</dpiAware>
+    </ms_asmv3:windowsSettings>
+  </ms_asmv3:application>
   <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
     <application>
       <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}" />
diff --git a/ipc/app/Makefile.in b/ipc/app/Makefile.in
index 193fada19ee..282e136b449 100644
--- a/ipc/app/Makefile.in
+++ b/ipc/app/Makefile.in
@@ -70,6 +70,7 @@ include $(topsrcdir)/config/rules.mk
 LDFLAGS += $(MOZ_ALLOW_HEAP_EXECUTE_FLAGS)
 
 ifeq ($(OS_ARCH),WINNT) #{
+EXTRA_DEPS += $(PROGRAM).manifest
 #
 # Control the default heap size.
 # This is the heap returned by GetProcessHeap().
diff --git a/ipc/app/plugin-container.exe.manifest b/ipc/app/plugin-container.exe.manifest
index 791d7b4dcf2..6932a0054ae 100644
--- a/ipc/app/plugin-container.exe.manifest
+++ b/ipc/app/plugin-container.exe.manifest
@@ -26,6 +26,11 @@
       </ms_asmv3:requestedPrivileges>
     </ms_asmv3:security>
   </ms_asmv3:trustInfo>
+  <ms_asmv3:application xmlns:ms_asmv3="urn:schemas-microsoft-com:asm.v3">
+    <ms_asmv3:windowsSettings xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">
+      <dpiAware>true</dpiAware>
+    </ms_asmv3:windowsSettings>
+  </ms_asmv3:application>
   <compatibility xmlns="urn:schemas-microsoft-com:compatibility.v1">
     <application>
       <supportedOS Id="{35138b9a-5d96-4fbd-8e2d-a2440225f93a}" />
diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index c6eb8171119..d4184ffcb8e 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -2849,18 +2849,6 @@ XREMain::XRE_mainInit(bool* aExitFlag)
   }
 #endif
 
-#ifdef XP_WIN
-  {
-    // Vista API.  Mozilla is DPI Aware.
-    typedef BOOL (*SetProcessDPIAwareFunc)(VOID);
-    SetProcessDPIAwareFunc setDPIAware = (SetProcessDPIAwareFunc)
-      GetProcAddress(LoadLibraryW(L"user32.dll"), "SetProcessDPIAware");
-    if (setDPIAware) {
-      setDPIAware();
-    }
-  }
-#endif
-
   SetupErrorHandling(gArgv[0]);
 
 #ifdef CAIRO_HAS_DWRITE_FONT