diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 7681a60..127784d 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -143,6 +143,22 @@
   makeint("boot_size")
 
   d["fstab"] = LoadRecoveryFSTab(zip)
+  d["build.prop"] = LoadBuildProp(zip)
+  return d
+
+def LoadBuildProp(zip):
+  try:
+    data = zip.read("SYSTEM/build.prop")
+  except KeyError:
+    print "Warning: could not find SYSTEM/build.prop in %s" % zip
+    data = ""
+
+  d = {}
+  for line in data.split("\n"):
+    line = line.strip()
+    if not line or line.startswith("#"): continue
+    name, value = line.split("=", 1)
+    d[name] = value
   return d
 
 def LoadRecoveryFSTab(zip):
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index b8fe68c..3cd271a 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -303,8 +303,8 @@
                   whole_file=True)
 
 
-def AppendAssertions(script, input_zip):
-  device = GetBuildProp("ro.product.device", input_zip)
+def AppendAssertions(script, info_dict):
+  device = GetBuildProp("ro.product.device", info_dict)
   script.AssertDevice(device)
 
 
@@ -358,9 +358,12 @@
   # change very often.
   script = edify_generator.EdifyGenerator(3, OPTIONS.info_dict)
 
-  metadata = {"post-build": GetBuildProp("ro.build.fingerprint", input_zip),
-              "pre-device": GetBuildProp("ro.product.device", input_zip),
-              "post-timestamp": GetBuildProp("ro.build.date.utc", input_zip),
+  metadata = {"post-build": GetBuildProp("ro.build.fingerprint",
+                                         OPTIONS.info_dict),
+              "pre-device": GetBuildProp("ro.product.device",
+                                         OPTIONS.info_dict),
+              "post-timestamp": GetBuildProp("ro.build.date.utc",
+                                             OPTIONS.info_dict),
               }
 
   device_specific = common.DeviceSpecificParams(
@@ -373,10 +376,10 @@
       info_dict=OPTIONS.info_dict)
 
   if not OPTIONS.omit_prereq:
-    ts = GetBuildProp("ro.build.date.utc", input_zip)
+    ts = GetBuildProp("ro.build.date.utc", OPTIONS.info_dict)
     script.AssertOlderBuild(ts)
 
-  AppendAssertions(script, input_zip)
+  AppendAssertions(script, OPTIONS.info_dict)
   device_specific.FullOTA_Assertions()
   device_specific.FullOTA_InstallBegin()
 
@@ -446,16 +449,12 @@
   return out
 
 
-def GetBuildProp(property, z):
-  """Return the fingerprint of the build of a given target-files
-  ZipFile object."""
-  bp = z.read("SYSTEM/build.prop")
-  if not property:
-    return bp
-  m = re.search(re.escape(property) + r"=(.*)\n", bp)
-  if not m:
+def GetBuildProp(prop, info_dict):
+  """Return the fingerprint of the build of a given target-files info_dict."""
+  try:
+    return info_dict.get("build.prop", {})[prop]
+  except KeyError:
     raise common.ExternalError("couldn't find %s in build.prop" % (property,))
-  return m.group(1).strip()
 
 
 def WriteIncrementalOTAPackage(target_zip, source_zip, output_zip):
@@ -465,10 +464,13 @@
   if source_version == 0:
     print ("WARNING: generating edify script for a source that "
            "can't install it.")
-  script = edify_generator.EdifyGenerator(source_version, OPTIONS.target_info_dict)
+  script = edify_generator.EdifyGenerator(source_version,
+                                          OPTIONS.target_info_dict)
 
-  metadata = {"pre-device": GetBuildProp("ro.product.device", source_zip),
-              "post-timestamp": GetBuildProp("ro.build.date.utc", target_zip),
+  metadata = {"pre-device": GetBuildProp("ro.product.device",
+                                         OPTIONS.source_info_dict),
+              "post-timestamp": GetBuildProp("ro.build.date.utc",
+                                             OPTIONS.target_info_dict),
               }
 
   device_specific = common.DeviceSpecificParams(
@@ -522,8 +524,8 @@
       patch_list.append((tf.name, tf, sf, tf.size, common.sha1(d).hexdigest()))
       largest_source_size = max(largest_source_size, sf.size)
 
-  source_fp = GetBuildProp("ro.build.fingerprint", source_zip)
-  target_fp = GetBuildProp("ro.build.fingerprint", target_zip)
+  source_fp = GetBuildProp("ro.build.fingerprint", OPTIONS.source_info_dict)
+  target_fp = GetBuildProp("ro.build.fingerprint", OPTIONS.target_info_dict)
   metadata["pre-build"] = source_fp
   metadata["post-build"] = target_fp
 
@@ -550,7 +552,7 @@
   #  0.1 for unpacking verbatim files, symlinking, and doing the
   #      device-specific commands.
 
-  AppendAssertions(script, target_zip)
+  AppendAssertions(script, OPTIONS.target_info_dict)
   device_specific.IncrementalOTA_Assertions()
 
   script.Print("Verifying current system...")