diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 93e14e5..bc6eb24 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -703,7 +703,7 @@
     for partition in PARTITIONS_WITH_CARE_MAP:
       fingerprint = build_info.GetPartitionFingerprint(partition)
       if fingerprint:
-        d["avb_{}_salt".format(partition)] = sha256(fingerprint).hexdigest()
+        d["avb_{}_salt".format(partition)] = sha256(fingerprint.encode()).hexdigest()
 
   return d