diff --git a/installer/mosquitto.nsi b/installer/mosquitto.nsi
index 230d923b..2f8538d9 100644
--- a/installer/mosquitto.nsi
+++ b/installer/mosquitto.nsi
@@ -9,7 +9,7 @@
 !define env_hklm 'HKLM "SYSTEM\CurrentControlSet\Control\Session Manager\Environment"'
 
 Name "Eclipse Mosquitto"
-!define VERSION 2.0.21
+!define VERSION 2.0.21a
 OutFile "mosquitto-${VERSION}-install-windows-x86.exe"
 
 InstallDir "$PROGRAMFILES\mosquitto"
diff --git a/installer/mosquitto64.nsi b/installer/mosquitto64.nsi
index faff0e9a..efb71a70 100644
--- a/installer/mosquitto64.nsi
+++ b/installer/mosquitto64.nsi
@@ -9,7 +9,7 @@
 !define env_hklm 'HKLM "SYSTEM\CurrentControlSet\Control\Session Manager\Environment"'
 
 Name "Eclipse Mosquitto"
-!define VERSION 2.0.21
+!define VERSION 2.0.21a
 OutFile "mosquitto-${VERSION}-install-windows-x64.exe"
 
 !include "x64.nsh"