diff --git a/cmake/sample_defs/cpu1_platform_cfg.h b/cmake/sample_defs/cpu1_platform_cfg.h
index 167eedd53..4a7f608e9 100644
--- a/cmake/sample_defs/cpu1_platform_cfg.h
+++ b/cmake/sample_defs/cpu1_platform_cfg.h
@@ -178,7 +178,8 @@
 **       The recommended case to to have this value the same across all mission platforms
 **
 **  \par Limits
-**       This parameter has a lower limit of 1 and an upper limit of 0xFFFF. 
+**       This parameter has a lower limit of 1 and an upper limit of 0xFFFF. Note there
+**       is one MsgId value reserved as invalid, so the table is this size + 1. 
 */
 #define CFE_PLATFORM_SB_HIGHEST_VALID_MSGID      0x1FFF
 
diff --git a/fsw/cfe-core/src/sb/cfe_sb_priv.h b/fsw/cfe-core/src/sb/cfe_sb_priv.h
index 86201fd47..37335e3a7 100644
--- a/fsw/cfe-core/src/sb/cfe_sb_priv.h
+++ b/fsw/cfe-core/src/sb/cfe_sb_priv.h
@@ -119,7 +119,7 @@
 **           be used directly, except by internal table lookups.
 **
 */
-typedef uint16  CFE_SB_MsgKey_Atom_t;
+typedef uint32  CFE_SB_MsgKey_Atom_t;
 
 /******************************************************************************
 **  Typedef:  CFE_SB_MsgKey_t