diff --git a/tools/install/win/lazarus-cross.iss b/tools/install/win/lazarus-cross.iss
index 74b4a821c5..e69266af58 100644
--- a/tools/install/win/lazarus-cross.iss
+++ b/tools/install/win/lazarus-cross.iss
@@ -6,8 +6,12 @@ EnableISX=true
 // A valid file version contains only digits, so drop the RC part
 #if pos('RC',AppVersion)>0
   #define FileVersion = copy(AppVersion, 1, pos('RC', AppVersion)-1)
-#else
-  #define FileVersion = AppVersion
+#else 
+  #if pos('pre',AppVersion)>0
+    #define FileVersion = copy(AppVersion, 1, pos('pre', AppVersion)-1)
+  #else
+    #define FileVersion = AppVersion
+  #endif
 #endif
 #define LazRevision GetEnv('LazRevision')
 #define FPCVersion GetEnv('FPCVersion')
diff --git a/tools/install/win/lazarus.iss b/tools/install/win/lazarus.iss
index 91c5eda563..19e59193b2 100644
--- a/tools/install/win/lazarus.iss
+++ b/tools/install/win/lazarus.iss
@@ -6,8 +6,12 @@ EnableISX=true
 // A valid file version contains only digits, so drop the RC part
 #if pos('RC',AppVersion)>0
   #define FileVersion = copy(AppVersion, 1, pos('RC', AppVersion)-1)
-#else
-  #define FileVersion = AppVersion
+#else 
+  #if pos('pre',AppVersion)>0
+    #define FileVersion = copy(AppVersion, 1, pos('pre', AppVersion)-1)
+  #else
+    #define FileVersion = AppVersion
+  #endif
 #endif
 #define FPCVersion GetEnv('FPCVersion')
 #define FPCTargetOS GetEnv('FPCTargetOS')