diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b006481..4ca725e 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -20,6 +20,8 @@ jobs:
         run: printf '%s\n' "$KEYS" > include/keys.inc
       - name: build
         shell: msys2 {0}
+        env:
+          DATECODE: ${{ github.ref_name }}
         run: sh build.cmd
       - uses: actions/upload-artifact@v4
         with:
@@ -39,6 +41,8 @@ jobs:
           KEYS: ${{ secrets.KEYS_INC }}
         run: printf '%s\n' "$KEYS" > include/keys.inc
       - run: sed 's/\r$//' build.cmd | sh
+        env:
+          DATECODE: ${{ github.ref_name }}
       - uses: actions/upload-artifact@v4
         with:
           name: linux-x64
diff --git a/build.cmd b/build.cmd
index d7af4e0..2e33f40 100644
--- a/build.cmd
+++ b/build.cmd
@@ -5,17 +5,19 @@ goto :WINDOWS
 #!/bin/sh
 set -e
 mkdir -p build
-DATESTR=$(date +%Y%m%d)
-REV=-1
-TAG_REV=$(git tag -l "${DATESTR}*" 2>/dev/null | sed "s/^${DATESTR}//" | sort -rn | head -1)
-[ -n "$TAG_REV" ] && REV=$((10#$TAG_REV))
-if [ -f build/.buildrev ]; then
-    read LAST_DATE LAST_REV < build/.buildrev
-    [ "$LAST_DATE" = "$DATESTR" ] && [ "$LAST_REV" -gt "$REV" ] && REV=$LAST_REV
+if [ -z "$DATECODE" ]; then
+    DATESTR=$(date +%Y%m%d)
+    REV=-1
+    TAG_REV=$(git tag -l "${DATESTR}*" 2>/dev/null | sed "s/^${DATESTR}//" | sort -rn | head -1)
+    [ -n "$TAG_REV" ] && REV=$(expr "$TAG_REV" + 0)
+    if [ -f build/.buildrev ]; then
+        read LAST_DATE LAST_REV < build/.buildrev
+        [ "$LAST_DATE" = "$DATESTR" ] && [ "$LAST_REV" -gt "$REV" ] && REV=$LAST_REV
+    fi
+    REV=$((REV + 1))
+    DATECODE=$(printf "%s%02d" "$DATESTR" "$REV")
+    echo "$DATESTR $REV" > build/.buildrev
 fi
-REV=$((REV + 1))
-DATECODE=$(printf "%s%02d" "$DATESTR" "$REV")
-echo "$DATESTR $REV" > build/.buildrev
 
 SRC="src/lib.c src/main.c src/crypto.c src/keys.c src/exfat.c src/ntfs.c src/stream.c src/aes.c"
 
@@ -75,6 +77,7 @@ for %%L in (
 set CFLAGS=-target x86_64-pc-windows-gnu -Oz -maes -msse4.1 -I include -fno-asynchronous-unwind-tables -fno-ident -ffunction-sections -fdata-sections -flto -ffreestanding -fno-builtin -fno-stack-protector -nostdlib -fno-unwind-tables -fno-exceptions -fmerge-all-constants -fno-addrsig
 set LDFLAGS=-fuse-ld=lld -Wl,--gc-sections -Wl,--icf=all -Wl,-e,_start -Wl,--subsystem,console -Wl,-s -Wl,--lto-Oz %LIBPATH%
 
+if defined DATECODE goto :buildstart
 for /f %%a in ('wmic os get localdatetime /value ^| find "="') do for /f "tokens=2 delims==" %%b in ("%%a") do set "DT=%%b"
 set "DATESTR=%DT:~0,8%"
 set REV=-1