diff --git a/android/config.go b/android/config.go
index c9d7dab..a81b928 100644
--- a/android/config.go
+++ b/android/config.go
@@ -570,8 +570,8 @@
 	return String(c.productVariables.BuildId)
 }
 
-func (c *config) BuildNumberFromFile() string {
-	return String(c.productVariables.BuildNumberFromFile)
+func (c *config) BuildNumberFile(ctx PathContext) Path {
+	return PathForOutput(ctx, String(c.productVariables.BuildNumberFile))
 }
 
 // DeviceName returns the name of the current device target
diff --git a/android/variable.go b/android/variable.go
index 06bd4ed..e4dd9fc 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -140,9 +140,8 @@
 	// Suffix to add to generated Makefiles
 	Make_suffix *string `json:",omitempty"`
 
-	BuildId             *string `json:",omitempty"`
-	BuildNumberFromFile *string `json:",omitempty"`
-	DateFromFile        *string `json:",omitempty"`
+	BuildId         *string `json:",omitempty"`
+	BuildNumberFile *string `json:",omitempty"`
 
 	Platform_version_name                     *string  `json:",omitempty"`
 	Platform_sdk_version                      *int     `json:",omitempty"`
@@ -347,7 +346,7 @@
 
 func (v *productVariables) SetDefaultConfig() {
 	*v = productVariables{
-		BuildNumberFromFile: stringPtr("123456789"),
+		BuildNumberFile: stringPtr("build_number.txt"),
 
 		Platform_version_name:             stringPtr("Q"),
 		Platform_sdk_version:              intPtr(28),