diff --git a/README.md b/README.md
index 39572f0a3..4626ee14e 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,11 @@ The autogenerated OSAL user's guide can be viewed at <https://github.com/nasa/cF
 
 ## Version History
 
+### Development Build: 5.1.0-rc1+dev38
+- Sets Revision to 99 for development builds
+- See <https://github.com/nasa/osal/pull/600>
+
+
 ### Development Build: 5.1.0-rc1+dev34
 
 - Move this existing function into the public API, as it is performs more verification than the OS_ConvertToArrayIndex
diff --git a/src/os/inc/osapi-version.h b/src/os/inc/osapi-version.h
index 91e9a9a19..e6d986d54 100644
--- a/src/os/inc/osapi-version.h
+++ b/src/os/inc/osapi-version.h
@@ -30,7 +30,7 @@
 /*
  * Development Build Macro Definitions
  */
-#define OS_BUILD_NUMBER 34 
+#define OS_BUILD_NUMBER 38 
 #define OS_BUILD_BASELINE "v5.1.0-rc1"
 
 /*
@@ -38,7 +38,7 @@
  */
 #define OS_MAJOR_VERSION 5 /*!< @brief ONLY APPLY for OFFICIAL releases. Major version number. */
 #define OS_MINOR_VERSION 0 /*!< @brief ONLY APPLY for OFFICIAL releases. Minor version number. */
-#define OS_REVISION      0 /*!< @brief ONLY APPLY for OFFICIAL releases. Revision number. */
+#define OS_REVISION      99/*!< @brief ONLY APPLY for OFFICIAL releases. Revision version number. If set to "99" it indicates a development version.  */
 #define OS_MISSION_REV   0 /*!< @brief ONLY USED by MISSION Implementations. Mission revision */
 
 /*