diff --git a/common/utils.h b/common/utils.h
index cbc5eb9..ecb97a3 100644
--- a/common/utils.h
+++ b/common/utils.h
@@ -21,6 +21,7 @@
 #include <unistd.h>
 
 #include <algorithm>
+#include <limits>
 #include <map>
 #include <memory>
 #include <set>
@@ -322,6 +323,13 @@
 // first section of |version| is invalid (e.g. not a number).
 int VersionPrefix(const std::string& version);
 
+// Parses a string in the form high.low, where high and low are 16 bit unsigned
+// integers. If there is more than 1 dot, or if either of the two parts are
+// not valid 16 bit unsigned numbers, then 0xffff is returned for both.
+void ParseRollbackKeyVersion(const std::string& raw_version,
+                             uint16_t* high_version,
+                             uint16_t* low_version);
+
 }  // namespace utils