diff --git a/DEPLOY.BAT b/DEPLOY.BAT
index aaaaba4..cf16109 100644
--- a/DEPLOY.BAT
+++ b/DEPLOY.BAT
@@ -268,9 +268,12 @@ REM This ensures it's set before any scripts or commands run
 IF NOT EXIST C:\AUTOEXEC.BAT GOTO CREATE_NEW_AUTOEXEC
 
 REM AUTOEXEC.BAT exists - insert SET MACHINE at line 2 (after @ECHO OFF)
+REM Use intermediate files - DOS 6.22 cannot handle double pipes with redirection
 ECHO @ECHO OFF > C:\AUTOEXEC.TMP
 ECHO SET MACHINE=%MACHINE% >> C:\AUTOEXEC.TMP
-TYPE C:\AUTOEXEC.BAT | FIND /V "@ECHO OFF" >> C:\AUTOEXEC.TMP
+TYPE C:\AUTOEXEC.BAT | FIND /V "@ECHO OFF" > C:\AUTOEXEC.TM1
+TYPE C:\AUTOEXEC.TM1 >> C:\AUTOEXEC.TMP
+DEL C:\AUTOEXEC.TM1
 COPY C:\AUTOEXEC.TMP C:\AUTOEXEC.BAT >NUL
 DEL C:\AUTOEXEC.TMP
 GOTO MACHINE_ADD_DONE
@@ -296,11 +299,16 @@ ECHO Updating to: SET MACHINE=%MACHINE%
 ECHO.
 
 REM Remove old SET MACHINE= line and insert new one at beginning
+REM Use intermediate files - DOS 6.22 cannot handle double pipes with redirection
 ECHO @ECHO OFF > C:\AUTOEXEC.TMP
 ECHO SET MACHINE=%MACHINE% >> C:\AUTOEXEC.TMP
 
-REM Append rest of AUTOEXEC.BAT, excluding @ECHO OFF and old SET MACHINE= lines
-TYPE C:\AUTOEXEC.BAT | FIND /V "@ECHO OFF" | FIND /V "SET MACHINE=" >> C:\AUTOEXEC.TMP
+REM Filter out @ECHO OFF and SET MACHINE= lines in separate steps
+TYPE C:\AUTOEXEC.BAT | FIND /V "@ECHO OFF" > C:\AUTOEXEC.TM1
+TYPE C:\AUTOEXEC.TM1 | FIND /V "SET MACHINE=" > C:\AUTOEXEC.TM2
+TYPE C:\AUTOEXEC.TM2 >> C:\AUTOEXEC.TMP
+DEL C:\AUTOEXEC.TM1
+DEL C:\AUTOEXEC.TM2
 
 REM Replace original with updated version
 COPY C:\AUTOEXEC.TMP C:\AUTOEXEC.BAT >NUL
diff --git a/check-dos-compatibility.ps1 b/check-dos-compatibility.ps1
index 6459a52..2856bc2 100644
--- a/check-dos-compatibility.ps1
+++ b/check-dos-compatibility.ps1
@@ -30,6 +30,7 @@ $IncompatiblePatterns = @(
     @{Pattern='IF.*\('; Description='IF ( ... ) multi-line blocks - NOT in DOS 6.22 (use GOTO labels)'},
     @{Pattern='\)\s*ELSE\s*\('; Description=') ELSE ( clause - NOT in DOS 6.22 (use GOTO labels)'},
     @{Pattern='^PAUSE\s+'; Description='PAUSE message - NOT in DOS 6.22 (use ECHO then PAUSE)'},
+    @{Pattern='\|.*\|.*>>'; Description='Double pipe with redirect (|..|..>>) - NOT reliable in DOS 6.22 (use temp files)'},
     @{Pattern='CHOICE\s+/[A-Z]'; Description='CHOICE with options - Check if CHOICE.COM available'},
     @{Pattern='START\s+'; Description='START command - NOT in DOS 6.22'}
 )