diff --git a/Contrib/nsDialogs/nsDialogs.nsh b/Contrib/nsDialogs/nsDialogs.nsh
index d782ceb0..2a9d2480 100644
--- a/Contrib/nsDialogs/nsDialogs.nsh
+++ b/Contrib/nsDialogs/nsDialogs.nsh
@@ -272,6 +272,7 @@
 !insertmacro __NSD_DefineCallback Click
 !insertmacro __NSD_DefineCallback Change
 !insertmacro __NSD_DefineCallback Notify
+!insertmacro __NSD_DefineCallback Back
 
 !define DEBUG `System::Call kernel32::OutputDebugString(ts)`