diff --git a/mozilla/toolkit/mozapps/installer/windows/nsis/common.nsh b/mozilla/toolkit/mozapps/installer/windows/nsis/common.nsh
index 1a6a3721372..009b42f4eaf 100755
--- a/mozilla/toolkit/mozapps/installer/windows/nsis/common.nsh
+++ b/mozilla/toolkit/mozapps/installer/windows/nsis/common.nsh
@@ -67,11 +67,15 @@ Exch 1   ; exchange the top of the stack with 2 below the top of the stack
 Exch $R9 ; exchange the new $R9 value with the top of the stack
 */
 
-# Commented out until the Thunderbird, Seamonkey, and Calendar Tinderboxes
-# have been updated to MozillaBuild which includes an updated version of
-# NSIS
-# !include TextFunc.nsh
-# !include FileFunc.nsh
+; When including a file provided by NSIS check if its verbose macro is defined
+; to prevent loading the file a second time.
+!ifmacrondef TEXTFUNC_VERBOSE
+!include TextFunc.nsh
+!endif
+
+!ifmacrondef FILEFUNC_VERBOSE
+!include FileFunc.nsh
+!endif
 
 ; NSIS provided macros that we have overridden.
 !include overrides.nsh
diff --git a/mozilla/toolkit/mozapps/installer/windows/nsis/overrides.nsh b/mozilla/toolkit/mozapps/installer/windows/nsis/overrides.nsh
index a3bf09006d5..899e71dae61 100755
--- a/mozilla/toolkit/mozapps/installer/windows/nsis/overrides.nsh
+++ b/mozilla/toolkit/mozapps/installer/windows/nsis/overrides.nsh
@@ -4,11 +4,15 @@
 !ifndef OVERRIDES_INCLUDED
 !define OVERRIDES_INCLUDED
 
-# Commented out until the Thunderbird, Seamonkey, and Calendar Tinderboxes
-# have been updated to MozillaBuild which includes an updated version of
-# NSIS
-# !include TextFunc.nsh
-# !include FileFunc.nsh
+; When including a file check if its verbose macro is defined to prevent
+; loading the file a second time.
+!ifmacrondef TEXTFUNC_VERBOSE
+!include TextFunc.nsh
+!endif
+
+!ifmacrondef FILEFUNC_VERBOSE
+!include FileFunc.nsh
+!endif
 
 ; Modified version of Locate from the NSIS File Functions Header v3.2
 ; This version has the calls to SetDetailsPrint and DetailsPrint commented out.