diff --git a/fsw/cfe-core/src/es/cfe_es_apps.c b/fsw/cfe-core/src/es/cfe_es_apps.c
index 0fe030b50..66fe5fe18 100644
--- a/fsw/cfe-core/src/es/cfe_es_apps.c
+++ b/fsw/cfe-core/src/es/cfe_es_apps.c
@@ -155,7 +155,7 @@ void CFE_ES_StartApplications(uint32 ResetType, const char *StartFilePath )
       while(1)
       {
          ReadStatus = OS_read(AppFile, &c, 1);
-         if ( ReadStatus == OS_FS_ERROR )
+         if ( ReadStatus == OS_ERROR )
          {
             CFE_ES_WriteToSysLog ("ES Startup: Error Reading Startup file. EC = 0x%08X\n",(unsigned int)ReadStatus);
             break;
diff --git a/fsw/cfe-core/src/es/cfe_es_shell.c b/fsw/cfe-core/src/es/cfe_es_shell.c
index 72a0ea1bc..adbe17e35 100644
--- a/fsw/cfe-core/src/es/cfe_es_shell.c
+++ b/fsw/cfe-core/src/es/cfe_es_shell.c
@@ -69,9 +69,9 @@ int32 CFE_ES_ShellOutputCommand(const char * CmdString, const char *Filename)
 
     fd = OS_creat(Filename, OS_READ_WRITE);
 
-    if (fd < OS_FS_SUCCESS)
+    if (fd < OS_SUCCESS)
     {
-        Result = OS_FS_ERROR;
+        Result = OS_ERROR;
     }
 
     else
@@ -113,11 +113,11 @@ int32 CFE_ES_ShellOutputCommand(const char * CmdString, const char *Filename)
         /* seek to the end of the file to get it's size */
         FileSize = OS_lseek(fd,0,OS_SEEK_END);
 
-        if (FileSize == OS_FS_ERROR)
+        if (FileSize == OS_ERROR)
         {
             OS_close(fd);
             CFE_ES_WriteToSysLog("OS_lseek call failed from CFE_ES_ShellOutputCmd 1\n");
-            Result =  OS_FS_ERROR;
+            Result =  OS_ERROR;
         }
 
 
@@ -153,11 +153,11 @@ int32 CFE_ES_ShellOutputCommand(const char * CmdString, const char *Filename)
             /* seek to the end of the file again to get it's new size */
             FileSize = OS_lseek(fd,0,OS_SEEK_END);
 
-            if (FileSize == OS_FS_ERROR)
+            if (FileSize == OS_ERROR)
             {
                 OS_close(fd);
                 CFE_ES_WriteToSysLog("OS_lseek call failed from CFE_ES_ShellOutputCmd 2\n");
-                Result =  OS_FS_ERROR;
+                Result =  OS_ERROR;
             }
 
 
@@ -210,9 +210,9 @@ int32 CFE_ES_ShellOutputCommand(const char * CmdString, const char *Filename)
    
                 /* Close the file descriptor */
                 OS_close(fd);
-            } /* if FilseSize == OS_FS_ERROR */
-        } /* if FileSeize == OS_FS_ERROR */
-    }/* if fd < OS_FS_SUCCESS */
+            } /* if FilseSize == OS_ERROR */
+        } /* if FileSeize == OS_ERROR */
+    }/* if fd < OS_SUCCESS */
 
 
     /* cppcheck-suppress duplicateExpression */
diff --git a/fsw/cfe-core/src/es/cfe_es_start.c b/fsw/cfe-core/src/es/cfe_es_start.c
index 2cb6383ba..e1ccc24a9 100644
--- a/fsw/cfe-core/src/es/cfe_es_start.c
+++ b/fsw/cfe-core/src/es/cfe_es_start.c
@@ -540,7 +540,7 @@ void CFE_ES_InitializeFileSystems(uint32 StartType)
    if ( StartType == CFE_PSP_RST_TYPE_POWERON )
    {
       RetStatus = OS_mkfs((void *)RamDiskMemoryAddress, "/ramdev0", "RAM", CFE_PLATFORM_ES_RAM_DISK_SECTOR_SIZE, CFE_PLATFORM_ES_RAM_DISK_NUM_SECTORS );
-      if ( RetStatus != OS_FS_SUCCESS )
+      if ( RetStatus != OS_SUCCESS )
       {
          CFE_ES_WriteToSysLog("ES Startup: Error Creating Volatile(RAM) Volume. EC = 0x%08X\n",(unsigned int)RetStatus);
 
@@ -558,7 +558,7 @@ void CFE_ES_InitializeFileSystems(uint32 StartType)
    else
    {
       RetStatus = OS_initfs((void *)RamDiskMemoryAddress, "/ramdev0", "RAM", CFE_PLATFORM_ES_RAM_DISK_SECTOR_SIZE, CFE_PLATFORM_ES_RAM_DISK_NUM_SECTORS );
-      if ( RetStatus != OS_FS_SUCCESS )
+      if ( RetStatus != OS_SUCCESS )
       {
          CFE_ES_WriteToSysLog("ES Startup: Error Initializing Volatile(RAM) Volume. EC = 0x%08X\n",(unsigned int)RetStatus);
          CFE_ES_WriteToSysLog("ES Startup: Formatting Volatile(RAM) Volume.\n");
@@ -586,7 +586,7 @@ void CFE_ES_InitializeFileSystems(uint32 StartType)
    ** Now, mount the RAM disk
    */
    RetStatus = OS_mount("/ramdev0", CFE_PLATFORM_ES_RAM_DISK_MOUNT_STRING);
-   if ( RetStatus != OS_FS_SUCCESS )
+   if ( RetStatus != OS_SUCCESS )
    {
       CFE_ES_WriteToSysLog("ES Startup: Error Mounting Volatile(RAM) Volume. EC = 0x%08X\n",(unsigned int)RetStatus);
       /*
@@ -642,14 +642,14 @@ void CFE_ES_InitializeFileSystems(uint32 StartType)
             ** First, unmount the disk
             */
             RetStatus = OS_unmount(CFE_PLATFORM_ES_RAM_DISK_MOUNT_STRING);
-            if ( RetStatus == OS_FS_SUCCESS )
+            if ( RetStatus == OS_SUCCESS )
             {
 
                /*
                ** Remove the file system from the OSAL
                */
                RetStatus = OS_rmfs("/ramdev0");
-               if ( RetStatus == OS_FS_SUCCESS )
+               if ( RetStatus == OS_SUCCESS )
                {
                
                   /*
@@ -658,13 +658,13 @@ void CFE_ES_InitializeFileSystems(uint32 StartType)
                   RetStatus = OS_mkfs((void *)RamDiskMemoryAddress, "/ramdev0", 
                                       "RAM", CFE_PLATFORM_ES_RAM_DISK_SECTOR_SIZE, 
                                        CFE_PLATFORM_ES_RAM_DISK_NUM_SECTORS );
-                  if ( RetStatus == OS_FS_SUCCESS )
+                  if ( RetStatus == OS_SUCCESS )
                   {
                      /*
                      ** Last, remount the disk
                      */
                      RetStatus = OS_mount("/ramdev0", CFE_PLATFORM_ES_RAM_DISK_MOUNT_STRING);
-                     if ( RetStatus != OS_FS_SUCCESS )
+                     if ( RetStatus != OS_SUCCESS )
                      {
                         CFE_ES_WriteToSysLog("ES Startup: Error Re-Mounting Volatile(RAM) Volume. EC = 0x%08X\n",(unsigned int)RetStatus);
                         /*
diff --git a/fsw/cfe-core/src/es/cfe_es_task.c b/fsw/cfe-core/src/es/cfe_es_task.c
index b04813991..2f750536e 100644
--- a/fsw/cfe-core/src/es/cfe_es_task.c
+++ b/fsw/cfe-core/src/es/cfe_es_task.c
@@ -1894,7 +1894,7 @@ int32 CFE_ES_DumpCDSRegistryCmd(const CFE_ES_DumpCDSRegistry_t *data)
     /* Create a new dump file, overwriting anything that may have existed previously */
     FileDescriptor = OS_creat(DumpFilename, OS_WRITE_ONLY);
 
-    if (FileDescriptor >= OS_FS_SUCCESS)
+    if (FileDescriptor >= OS_SUCCESS)
     {
         /* Initialize the standard cFE File Header for the Dump File */
         CFE_FS_InitHeader(&StdFileHeader, "CDS_Registry", CFE_FS_SubType_ES_CDS_REG);
diff --git a/fsw/cfe-core/src/evs/cfe_evs_log.c b/fsw/cfe-core/src/evs/cfe_evs_log.c
index ae90d0d7d..20751edc7 100644
--- a/fsw/cfe-core/src/evs/cfe_evs_log.c
+++ b/fsw/cfe-core/src/evs/cfe_evs_log.c
@@ -174,7 +174,7 @@ int32 CFE_EVS_WriteLogDataFileCmd(const CFE_EVS_WriteLogDataFile_t *data)
         /* Create the log file */
         LogFileHandle = OS_creat(LogFilename, OS_WRITE_ONLY);
 
-        if (LogFileHandle < OS_FS_SUCCESS)
+        if (LogFileHandle < OS_SUCCESS)
         {
             EVS_SendEvent(CFE_EVS_ERR_CRLOGFILE_EID, CFE_EVS_EventType_ERROR,
                     "Write Log File Command Error: OS_creat = 0x%08X, filename = %s",
diff --git a/fsw/cfe-core/src/evs/cfe_evs_task.c b/fsw/cfe-core/src/evs/cfe_evs_task.c
index 22ad6a2d0..fb0721a18 100644
--- a/fsw/cfe-core/src/evs/cfe_evs_task.c
+++ b/fsw/cfe-core/src/evs/cfe_evs_task.c
@@ -1753,7 +1753,7 @@ int32 CFE_EVS_WriteAppDataFileCmd(const CFE_EVS_WriteAppDataFile_t *data)
    /* Create Application Data File */
    FileHandle = OS_creat(LocalName, OS_WRITE_ONLY);
 
-   if (FileHandle < OS_FS_SUCCESS)
+   if (FileHandle < OS_SUCCESS)
    {
       EVS_SendEvent(CFE_EVS_ERR_CRDATFILE_EID, CFE_EVS_EventType_ERROR,
                    "Write App Data Command Error: OS_creat = 0x%08X, filename = %s",
diff --git a/fsw/cfe-core/src/fs/cfe_fs_api.c b/fsw/cfe-core/src/fs/cfe_fs_api.c
index 1c991ffeb..56f792350 100644
--- a/fsw/cfe-core/src/fs/cfe_fs_api.c
+++ b/fsw/cfe-core/src/fs/cfe_fs_api.c
@@ -191,7 +191,7 @@ int32 CFE_FS_SetTimestamp(int32 FileDes, CFE_TIME_SysTime_t NewTimestamp)
             
             if (Result == sizeof(OutTimestamp.Subseconds))
             {
-                Result = OS_FS_SUCCESS;
+                Result = OS_SUCCESS;
             }
             else
             {
diff --git a/fsw/cfe-core/src/inc/cfe_error.h b/fsw/cfe-core/src/inc/cfe_error.h
index e5ce58e2e..0e93b4a34 100644
--- a/fsw/cfe-core/src/inc/cfe_error.h
+++ b/fsw/cfe-core/src/inc/cfe_error.h
@@ -807,12 +807,12 @@
 #define CFE_OS_ERR_NAME_NOT_FOUND       (OS_ERR_NAME_NOT_FOUND)  /**< @brief DEPRECATED @deprecated */
 #define CFE_OS_ERR_SEM_NOT_FULL         (OS_ERR_SEM_NOT_FULL)  /**< @brief DEPRECATED @deprecated */
 #define CFE_OS_ERR_INVALID_PRIORITY     (OS_ERR_INVALID_PRIORITY)  /**< @brief DEPRECATED @deprecated */
-#define CFE_OS_FS_ERROR                 (OS_FS_ERROR)  /**< @brief DEPRECATED @deprecated */
-#define CFE_OS_FS_ERR_INVALID_POINTER   (OS_FS_ERR_INVALID_POINTER)  /**< @brief DEPRECATED @deprecated */
+#define CFE_OS_FS_ERROR                 (OS_ERROR)  /**< @brief DEPRECATED @deprecated */
+#define CFE_OS_FS_ERR_INVALID_POINTER   (OS_INVALID_POINTER)  /**< @brief DEPRECATED @deprecated */
 #define CFE_OS_FS_ERR_PATH_TOO_LONG     (OS_FS_ERR_PATH_TOO_LONG)  /**< @brief DEPRECATED @deprecated */
 #define CFE_OS_FS_ERR_NAME_TOO_LONG     (OS_FS_ERR_NAME_TOO_LONG)  /**< @brief DEPRECATED @deprecated */
 #define CFE_OS_FS_ERR_DRIVE_NOT_CREATED (OS_FS_ERR_DRIVE_NOT_CREATED)  /**< @brief DEPRECATED @deprecated */
-#define CFE_OSAPI_NOT_IMPLEMENTED       (OS_FS_UNIMPLEMENTED)  /**< @brief DEPRECATED @deprecated */
+#define CFE_OSAPI_NOT_IMPLEMENTED       (OS_ERR_NOT_IMPLEMENTED)  /**< @brief DEPRECATED @deprecated */
 
 #endif /* CFE_OMIT_DEPRECATED_6_7 */
 
diff --git a/fsw/cfe-core/src/sb/cfe_sb_task.c b/fsw/cfe-core/src/sb/cfe_sb_task.c
index 88e4cece2..9bb69d014 100644
--- a/fsw/cfe-core/src/sb/cfe_sb_task.c
+++ b/fsw/cfe-core/src/sb/cfe_sb_task.c
@@ -854,7 +854,7 @@ int32 CFE_SB_SendRtgInfo(const char *Filename)
     CFE_SB_DestinationD_t       *DestPtr;
 
     fd = OS_creat(Filename, OS_WRITE_ONLY);
-    if(fd < OS_FS_SUCCESS){
+    if(fd < OS_SUCCESS){
         CFE_EVS_SendEvent(CFE_SB_SND_RTG_ERR1_EID,CFE_EVS_EventType_ERROR,
                       "Error creating file %s, stat=0x%x",
                       Filename,(unsigned int)fd);
@@ -964,7 +964,7 @@ int32 CFE_SB_SendPipeInfo(const char *Filename)
 
     fd = OS_creat(Filename, OS_WRITE_ONLY);
 
-    if(fd < OS_FS_SUCCESS){
+    if(fd < OS_SUCCESS){
         CFE_EVS_SendEvent(CFE_SB_SND_RTG_ERR1_EID,CFE_EVS_EventType_ERROR,
                           "Error creating file %s, stat=0x%x",
                            Filename,(unsigned int)fd);
@@ -1039,7 +1039,7 @@ int32 CFE_SB_SendMapInfo(const char *Filename)
 
     fd = OS_creat(Filename, OS_WRITE_ONLY);
 
-    if (fd < OS_FS_SUCCESS){
+    if (fd < OS_SUCCESS){
         CFE_EVS_SendEvent(CFE_SB_SND_RTG_ERR1_EID,CFE_EVS_EventType_ERROR,
                           "Error creating file %s, stat=0x%x",
                            Filename,(unsigned int)fd);
diff --git a/fsw/cfe-core/src/tbl/cfe_tbl_internal.h b/fsw/cfe-core/src/tbl/cfe_tbl_internal.h
index 2e29002da..b09bb54a3 100644
--- a/fsw/cfe-core/src/tbl/cfe_tbl_internal.h
+++ b/fsw/cfe-core/src/tbl/cfe_tbl_internal.h
@@ -380,12 +380,12 @@ int32   CFE_TBL_GetWorkingBuffer(CFE_TBL_LoadBuff_t **WorkingBufferPtr,
 **                              of table image file to be loaded
 **
 ** \retval #CFE_SUCCESS                      \copydoc CFE_SUCCESS
-** \retval #OS_FS_ERR_INVALID_POINTER        \copydoc OS_FS_ERR_INVALID_POINTER      
+** \retval #OS_INVALID_POINTER               \copydoc OS_INVALID_POINTER      
 ** \retval #OS_FS_ERR_PATH_TOO_LONG          \copydoc OS_FS_ERR_PATH_TOO_LONG      
 ** \retval #OS_FS_ERR_PATH_INVALID           \copydoc OS_FS_ERR_PATH_INVALID      
 ** \retval #OS_FS_ERR_NAME_TOO_LONG          \copydoc OS_FS_ERR_NAME_TOO_LONG      
-** \retval #OS_FS_ERR_NO_FREE_FDS            \copydoc OS_FS_ERR_NO_FREE_FDS      
-** \retval #OS_FS_ERROR                      \copydoc OS_FS_ERROR      
+** \retval #OS_ERR_NO_FREE_IDS               \copydoc OS_ERR_NO_FREE_IDS      
+** \retval #OS_ERROR                         \copydoc OS_ERROR      
 ** \retval #CFE_TBL_ERR_FILE_TOO_LARGE       \copydoc CFE_TBL_ERR_FILE_TOO_LARGE      
 ** \retval #CFE_TBL_WARN_SHORT_FILE          \copydoc CFE_TBL_WARN_SHORT_FILE         
 ** \retval #CFE_TBL_WARN_PARTIAL_LOAD        \copydoc CFE_TBL_WARN_PARTIAL_LOAD       
diff --git a/fsw/cfe-core/src/tbl/cfe_tbl_task_cmds.c b/fsw/cfe-core/src/tbl/cfe_tbl_task_cmds.c
index e697ce72d..421ddbd7c 100644
--- a/fsw/cfe-core/src/tbl/cfe_tbl_task_cmds.c
+++ b/fsw/cfe-core/src/tbl/cfe_tbl_task_cmds.c
@@ -119,7 +119,7 @@ int32 CFE_TBL_HousekeepingCmd(const CCSDS_CommandPacket_t *data)
                 {
                     Status = CFE_FS_SetTimestamp(FileDescriptor, DumpTime);
                     
-                    if (Status != OS_FS_SUCCESS)
+                    if (Status != OS_SUCCESS)
                     {
                         CFE_ES_WriteToSysLog("CFE_TBL:HkCmd-Unable to update timestamp in dump file '%s'\n", 
                                              DumpCtrlPtr->DumpBufferPtr->DataSource);
@@ -757,7 +757,7 @@ CFE_TBL_CmdProcRet_t CFE_TBL_DumpToFile( const char *DumpFilename, const char *T
     /* Create a new dump file, overwriting anything that may have existed previously */
     FileDescriptor = OS_creat(DumpFilename, OS_WRITE_ONLY);
 
-    if (FileDescriptor >= OS_FS_SUCCESS)
+    if (FileDescriptor >= OS_SUCCESS)
     {
         /* Initialize the standard cFE File Header for the Dump File */
         CFE_FS_InitHeader(&StdFileHeader, "Table Dump Image", CFE_FS_SubType_TBL_IMG);
@@ -1147,7 +1147,7 @@ int32 CFE_TBL_DumpRegistryCmd(const CFE_TBL_DumpRegistry_t *data)
     /* Create a new dump file, overwriting anything that may have existed previously */
     FileDescriptor = OS_creat(DumpFilename, OS_WRITE_ONLY);
 
-    if (FileDescriptor >= OS_FS_SUCCESS)
+    if (FileDescriptor >= OS_SUCCESS)
     {
         /* Initialize the standard cFE File Header for the Dump File */
         CFE_FS_InitHeader(&StdFileHeader, "Table Registry", CFE_FS_SubType_TBL_REG);
diff --git a/fsw/cfe-core/unit-test/es_UT.c b/fsw/cfe-core/unit-test/es_UT.c
index ac7608c8d..e0a7a7ab3 100644
--- a/fsw/cfe-core/unit-test/es_UT.c
+++ b/fsw/cfe-core/unit-test/es_UT.c
@@ -3068,7 +3068,7 @@ void TestTask(void)
     /* Test write of all app data to file with a write header failure */
     ES_ResetUnitTest();
     memset(&CmdBuf, 0, sizeof(CmdBuf));
-    UT_SetDeferredRetcode(UT_KEY(CFE_FS_WriteHeader), 1, OS_FS_ERROR);
+    UT_SetDeferredRetcode(UT_KEY(CFE_FS_WriteHeader), 1, OS_ERROR);
     UT_CallTaskPipe(CFE_ES_TaskPipe, &CmdBuf.Msg, sizeof(CFE_ES_QueryAll_t),
             UT_TPID_CFE_ES_CMD_QUERY_ALL_CC);
     UT_Report(__FILE__, __LINE__,
@@ -3245,7 +3245,7 @@ void TestTask(void)
 
     /* Test writing the system log with a write header failure */
     ES_ResetUnitTest();
-    UT_SetDeferredRetcode(UT_KEY(CFE_FS_WriteHeader), 1, OS_FS_ERROR);
+    UT_SetDeferredRetcode(UT_KEY(CFE_FS_WriteHeader), 1, OS_ERROR);
     UT_CallTaskPipe(CFE_ES_TaskPipe, &CmdBuf.Msg, sizeof(CFE_ES_WriteSyslog_t),
             UT_TPID_CFE_ES_CMD_WRITE_SYSLOG_CC);
     UT_Report(__FILE__, __LINE__,
@@ -3304,7 +3304,7 @@ void TestTask(void)
     /* Test writing the E&R log with a write header failure */
     ES_ResetUnitTest();
     memset(&CmdBuf, 0, sizeof(CmdBuf));
-    UT_SetDeferredRetcode(UT_KEY(CFE_FS_WriteHeader), 1, OS_FS_ERROR);
+    UT_SetDeferredRetcode(UT_KEY(CFE_FS_WriteHeader), 1, OS_ERROR);
     UT_CallTaskPipe(CFE_ES_TaskPipe, &CmdBuf.Msg, sizeof(CFE_ES_WriteERLog_t),
             UT_TPID_CFE_ES_CMD_WRITE_ER_LOG_CC);
     UT_Report(__FILE__, __LINE__,
diff --git a/fsw/cfe-core/unit-test/fs_UT.c b/fsw/cfe-core/unit-test/fs_UT.c
index e24754f52..3993bed71 100644
--- a/fsw/cfe-core/unit-test/fs_UT.c
+++ b/fsw/cfe-core/unit-test/fs_UT.c
@@ -112,7 +112,7 @@ void Test_CFE_FS_ReadHeader(void)
 
     /* Test successfully reading the header */
     UT_InitData();
-    UT_SetDeferredRetcode(UT_KEY(OS_lseek), 1, OS_FS_SUCCESS);
+    UT_SetDeferredRetcode(UT_KEY(OS_lseek), 1, OS_SUCCESS);
     UT_SetForceFail(UT_KEY(OS_read), OS_ERROR);
     UT_Report(__FILE__, __LINE__,
               CFE_FS_ReadHeader(&Hdr, FileDes) != sizeof(CFE_FS_Header_t),
@@ -142,10 +142,10 @@ void Test_CFE_FS_WriteHeader(void)
 
     /* Test successfully writing the header */
     UT_InitData();
-    UT_SetDeferredRetcode(UT_KEY(OS_lseek), 1, OS_FS_SUCCESS);
-    UT_SetDeferredRetcode(UT_KEY(OS_write), 1, OS_FS_SUCCESS);
+    UT_SetDeferredRetcode(UT_KEY(OS_lseek), 1, OS_SUCCESS);
+    UT_SetDeferredRetcode(UT_KEY(OS_write), 1, OS_SUCCESS);
     UT_Report(__FILE__, __LINE__,
-              CFE_FS_WriteHeader(FileDes, &Hdr) == OS_FS_SUCCESS,
+              CFE_FS_WriteHeader(FileDes, &Hdr) == OS_SUCCESS,
               "CFE_FS_WriteHeader",
               "Header write - successful");
 }
@@ -166,7 +166,7 @@ void Test_CFE_FS_SetTimestamp(void)
     UT_InitData();
     UT_SetForceFail(UT_KEY(OS_lseek), OS_ERROR);
     UT_Report(__FILE__, __LINE__,
-              CFE_FS_SetTimestamp(FileDes, NewTimestamp) == OS_FS_ERROR,
+              CFE_FS_SetTimestamp(FileDes, NewTimestamp) == OS_ERROR,
               "CFE_FS_SetTimestamp",
               "Failed to lseek time fields");
 
@@ -189,7 +189,7 @@ void Test_CFE_FS_SetTimestamp(void)
     /* Test successfully setting the time stamp */
     UT_InitData();
     UT_Report(__FILE__, __LINE__,
-              CFE_FS_SetTimestamp(FileDes, NewTimestamp) == OS_FS_SUCCESS,
+              CFE_FS_SetTimestamp(FileDes, NewTimestamp) == OS_SUCCESS,
               "CFE_FS_SetTimestamp",
               "Write time stamp - successful");
 }
@@ -506,7 +506,7 @@ void Test_CFE_FS_Decompress(void)
     /* Test filling the input buffer with a FS error  */
     UT_InitData();
     UT_SetDeferredRetcode(UT_KEY(OS_read), 1, 4);
-    UT_SetDeferredRetcode(UT_KEY(OS_read), 1, OS_FS_ERROR);
+    UT_SetDeferredRetcode(UT_KEY(OS_read), 1, OS_ERROR);
     UT_Report(__FILE__, __LINE__,
               FS_gz_fill_inbuf_Reentrant(&UT_FS_Decompress_State) == EOF,
               "FS_gz_fill_inbuf",
diff --git a/fsw/cfe-core/unit-test/tbl_UT.c b/fsw/cfe-core/unit-test/tbl_UT.c
index f1fe98824..4164d8bd4 100644
--- a/fsw/cfe-core/unit-test/tbl_UT.c
+++ b/fsw/cfe-core/unit-test/tbl_UT.c
@@ -1761,7 +1761,7 @@ void Test_CFE_TBL_HousekeepingCmd(void)
     /* Test response to a file time stamp failure */
     UT_InitData();
     CFE_TBL_TaskData.DumpControlBlocks[0].State = CFE_TBL_DUMP_PERFORMED;
-    UT_SetDeferredRetcode(UT_KEY(CFE_FS_SetTimestamp), 1, OS_FS_SUCCESS - 1);
+    UT_SetDeferredRetcode(UT_KEY(CFE_FS_SetTimestamp), 1, OS_SUCCESS - 1);
     UT_Report(__FILE__, __LINE__,
               CFE_TBL_HousekeepingCmd(NULL) == CFE_TBL_DONT_INC_CTR,
               "CFE_TBL_HousekeepingCmd",
diff --git a/fsw/cfe-core/ut-stubs/ut_fs_stubs.c b/fsw/cfe-core/ut-stubs/ut_fs_stubs.c
index 6c7df8335..3b553fa42 100644
--- a/fsw/cfe-core/ut-stubs/ut_fs_stubs.c
+++ b/fsw/cfe-core/ut-stubs/ut_fs_stubs.c
@@ -146,13 +146,13 @@ int32 CFE_FS_ReadHeader(CFE_FS_Header_t *Hdr, int32 FileDes)
 **        being called.  If the value FSSetTimestampRtn.count is greater than
 **        zero then the counter is decremented; if it then equals zero the
 **        return value is set to the user-defined value
-**        FSSetTimestampRtn.value.  OS_FS_SUCCESS is returned otherwise.
+**        FSSetTimestampRtn.value.  OS_SUCCESS is returned otherwise.
 **
 ** \par Assumptions, External Events, and Notes:
 **        None
 **
 ** \returns
-**        Returns either a user-defined status flag or OS_FS_SUCCESS.
+**        Returns either a user-defined status flag or OS_SUCCESS.
 **
 ******************************************************************************/
 int32 CFE_FS_SetTimestamp(int32 FileDes, CFE_TIME_SysTime_t NewTimestamp)