diff --git a/Modules/CPackNSIS.cmake b/Modules/CPackNSIS.cmake
index 5e2ba17f8..66c33a8df 100644
--- a/Modules/CPackNSIS.cmake
+++ b/Modules/CPackNSIS.cmake
@@ -31,13 +31,21 @@
 ##end
 #
 ##variable
-#   CPACK_NSIS_EXTRA_INSTALL_COMMANDS - Extra NSIS commands that will
-#   be added to the install Section.
+#   CPACK_NSIS_EXTRA_PREINSTALL_COMMANDS - Extra NSIS commands that
+#   will be added to the beginning of the install Section, before your
+#   install tree is available on the target system.
+##end
+#
+##variable
+#   CPACK_NSIS_EXTRA_INSTALL_COMMANDS - Extra NSIS commands that
+#   will be added to the end of the install Section, after your
+#   install tree is available on the target system.
 ##end
 #
 ##variable
 #   CPACK_NSIS_EXTRA_UNINSTALL_COMMANDS - Extra NSIS commands that will
-#   be added to the uninstall Section.
+#   be added to the uninstall Section, before your install tree is
+#   removed from the target system.
 ##end
 #
 ##variable
diff --git a/Modules/NSIS.template.in b/Modules/NSIS.template.in
index 819cc5cc0..e7edead2a 100644
--- a/Modules/NSIS.template.in
+++ b/Modules/NSIS.template.in
@@ -637,6 +637,7 @@ Section "-Core installation"
   ;Use the entire tree produced by the INSTALL target.  Keep the
   ;list of directories here in sync with the RMDir commands below.
   SetOutPath "$INSTDIR"
+  @CPACK_NSIS_EXTRA_PREINSTALL_COMMANDS@
   @CPACK_NSIS_FULL_INSTALL@
   
   ;Store installation folder