diff --git a/bin/internal/update_dart_sdk.ps1 b/bin/internal/update_dart_sdk.ps1
index cb95257d92..dd7cafa53b 100644
--- a/bin/internal/update_dart_sdk.ps1
+++ b/bin/internal/update_dart_sdk.ps1
@@ -20,9 +20,16 @@ $cachePath = "$flutterRoot\bin\cache"
 $dartSdkPath = "$cachePath\dart-sdk"
 $dartSdkLicense = "$cachePath\LICENSE.dart_sdk_archive.md"
 $engineStamp = "$cachePath\engine-dart-sdk.stamp"
-$engineVersion = (Get-Content "$flutterRoot\bin\internal\engine.version")
 $engineRealm = (Get-Content "$flutterRoot\bin\internal\engine.realm")
 
+if (Test-Path "$flutterRoot\bin\internal\engine.version") {
+    $engineVersion = (Get-Content "$flutterRoot\bin\internal\engine.version")
+} else {
+    # Calculate the engine hash from tracked git files.
+    $lsTree = ((git ls-tree -r HEAD engine DEPS) | Out-String).Replace("`r`n", "`n")
+    $engineVersion = (Get-FileHash -InputStream ([System.IO.MemoryStream] [System.Text.Encoding]::UTF8.GetBytes($lsTree)) -Algorithm SHA1 | ForEach-Object { $_.Hash }).ToLower()
+}
+
 $oldDartSdkPrefix = "dart-sdk.old"
 
 # Make sure that PowerShell has expected version.
diff --git a/bin/internal/update_dart_sdk.sh b/bin/internal/update_dart_sdk.sh
index 8d7b3adf56..5c1ea23e8b 100755
--- a/bin/internal/update_dart_sdk.sh
+++ b/bin/internal/update_dart_sdk.sh
@@ -19,10 +19,18 @@ FLUTTER_ROOT="$(dirname "$(dirname "$(dirname "${BASH_SOURCE[0]}")")")"
 DART_SDK_PATH="$FLUTTER_ROOT/bin/cache/dart-sdk"
 DART_SDK_PATH_OLD="$DART_SDK_PATH.old"
 ENGINE_STAMP="$FLUTTER_ROOT/bin/cache/engine-dart-sdk.stamp"
-ENGINE_VERSION=$(cat "$FLUTTER_ROOT/bin/internal/engine.version")
 ENGINE_REALM=$(cat "$FLUTTER_ROOT/bin/internal/engine.realm" | tr -d '[:space:]')
 OS="$(uname -s)"
 
+ENGINE_VERSION=""
+if [ -f "$FLUTTER_ROOT/bin/internal/engine.version" ]; then
+  ENGINE_VERSION=$(cat "$FLUTTER_ROOT/bin/internal/engine.version")
+else
+  # Calculate the engine hash from tracked git files.
+  # The array takes the first part of the sha1sum string.
+  ENGINE_VERSION=($(git ls-tree HEAD -r engine DEPS | sha1sum))
+fi
+
 if [ ! -f "$ENGINE_STAMP" ] || [ "$ENGINE_VERSION" != `cat "$ENGINE_STAMP"` ]; then
   command -v curl > /dev/null 2>&1 || {
     >&2 echo