diff --git a/modules/cfe_testcase/src/message_id_test.c b/modules/cfe_testcase/src/message_id_test.c
index 235d1cf8d..2956c2895 100644
--- a/modules/cfe_testcase/src/message_id_test.c
+++ b/modules/cfe_testcase/src/message_id_test.c
@@ -42,7 +42,7 @@ void TestMsgId(void)
 
     UtAssert_INT32_EQ(CFE_MSG_SetMsgId(&msg, expectedmsgid), CFE_SUCCESS);
     UtAssert_INT32_EQ(CFE_MSG_GetMsgId(&msg, &msgid), CFE_SUCCESS);
-    UtAssert_UINT32_EQ(msgid, expectedmsgid);
+    CFE_Assert_MSGID_EQ(msgid, expectedmsgid);
 
     UtAssert_INT32_EQ(CFE_MSG_SetMsgId(NULL, msgid), CFE_MSG_BAD_ARGUMENT);
 
@@ -93,4 +93,4 @@ void MessageIdTestSetup(void)
 {
     UtTest_Add(TestMsgId, NULL, NULL, "Test Set/Get Message ID");
     UtTest_Add(TestGetTypeFromMsgId, NULL, NULL, "Test Get Type From Message ID");
-}
\ No newline at end of file
+}
diff --git a/modules/cfe_testcase/src/msg_api_test.c b/modules/cfe_testcase/src/msg_api_test.c
index 11e12f40d..d38096cf8 100644
--- a/modules/cfe_testcase/src/msg_api_test.c
+++ b/modules/cfe_testcase/src/msg_api_test.c
@@ -55,7 +55,7 @@ void TestMsgApiBasic(void)
     /* test msg-init */
     UtAssert_INT32_EQ(CFE_MSG_Init(NULL, CFE_SB_ValueToMsgId(0), sizeof(cmd)), CFE_MSG_BAD_ARGUMENT);
     UtAssert_INT32_EQ(CFE_MSG_Init(&cmd.Msg, msgId, 0), CFE_MSG_BAD_ARGUMENT);
-    UtAssert_INT32_EQ(CFE_MSG_Init(&cmd.Msg, CFE_PLATFORM_SB_HIGHEST_VALID_MSGID + 1, sizeof(cmd)),
+    UtAssert_INT32_EQ(CFE_MSG_Init(&cmd.Msg, CFE_SB_ValueToMsgId(CFE_PLATFORM_SB_HIGHEST_VALID_MSGID + 1), sizeof(cmd)),
                       CFE_MSG_BAD_ARGUMENT);
 
     UtAssert_INT32_EQ(CFE_MSG_Init(&cmd.Msg, msgId, sizeof(cmd)), CFE_SUCCESS);
diff --git a/modules/cfe_testcase/src/sb_subscription_test.c b/modules/cfe_testcase/src/sb_subscription_test.c
index 8e1745272..628360445 100644
--- a/modules/cfe_testcase/src/sb_subscription_test.c
+++ b/modules/cfe_testcase/src/sb_subscription_test.c
@@ -54,7 +54,6 @@ void TestSubscribeUnsubscribe(void)
 
     /* Subscribe - Confirm Bad MsgId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_Subscribe(CFE_SB_INVALID_MSG_ID, PipeId1), CFE_SB_BAD_ARGUMENT);
-    UtAssert_INT32_EQ(CFE_SB_Subscribe(CFE_SB_MSGID_RESERVED, PipeId2), CFE_SB_BAD_ARGUMENT);
 
     /* Subscribe - Confirm Bad PipeId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_Subscribe(CFE_FT_CMD_MSGID, CFE_SB_INVALID_PIPE), CFE_SB_BAD_ARGUMENT);
@@ -73,7 +72,6 @@ void TestSubscribeUnsubscribe(void)
 
     /* Unsubscribe - Confirm Bad MsgId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_Unsubscribe(CFE_SB_INVALID_MSG_ID, PipeId1), CFE_SB_BAD_ARGUMENT);
-    UtAssert_INT32_EQ(CFE_SB_Unsubscribe(CFE_SB_MSGID_RESERVED, PipeId2), CFE_SB_BAD_ARGUMENT);
 
     /* Unsubscribe - Confirm Bad PipeId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_Unsubscribe(CFE_FT_CMD_MSGID, CFE_SB_INVALID_PIPE), CFE_SB_BAD_ARGUMENT);
@@ -108,7 +106,6 @@ void TestSubscribeUnsubscribeLocal(void)
 
     /* Subscribe - Confirm Bad MsgId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_SubscribeLocal(CFE_SB_INVALID_MSG_ID, PipeId1, 2), CFE_SB_BAD_ARGUMENT);
-    UtAssert_INT32_EQ(CFE_SB_SubscribeLocal(CFE_SB_MSGID_RESERVED, PipeId2, 2), CFE_SB_BAD_ARGUMENT);
 
     /* Subscribe - Confirm Bad PipeId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_SubscribeLocal(CFE_FT_CMD_MSGID, CFE_SB_INVALID_PIPE, 2), CFE_SB_BAD_ARGUMENT);
@@ -127,7 +124,6 @@ void TestSubscribeUnsubscribeLocal(void)
 
     /* Unsubscribe - Confirm Bad MsgId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_UnsubscribeLocal(CFE_SB_INVALID_MSG_ID, PipeId1), CFE_SB_BAD_ARGUMENT);
-    UtAssert_INT32_EQ(CFE_SB_UnsubscribeLocal(CFE_SB_MSGID_RESERVED, PipeId2), CFE_SB_BAD_ARGUMENT);
 
     /* Unsubscribe - Confirm Bad PipeId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_UnsubscribeLocal(CFE_FT_CMD_MSGID, CFE_SB_INVALID_PIPE), CFE_SB_BAD_ARGUMENT);
@@ -174,7 +170,6 @@ void TestSubscribeEx(void)
 
     /* Subscribe - Confirm Bad MsgId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_SubscribeEx(CFE_SB_INVALID_MSG_ID, PipeId1, CFE_SB_DEFAULT_QOS, 2), CFE_SB_BAD_ARGUMENT);
-    UtAssert_INT32_EQ(CFE_SB_SubscribeEx(CFE_SB_MSGID_RESERVED, PipeId2, CFE_SB_DEFAULT_QOS, 2), CFE_SB_BAD_ARGUMENT);
 
     /* Subscribe - Confirm Bad PipeId Arg Rejection */
     UtAssert_INT32_EQ(CFE_SB_SubscribeEx(CFE_FT_CMD_MSGID, CFE_SB_INVALID_PIPE, CFE_SB_DEFAULT_QOS, 2),
@@ -214,7 +209,7 @@ void TestSBMaxSubscriptions(void)
     while (NumSubs <= CFE_PLATFORM_SB_MAX_MSG_IDS)
     {
         /* fabricate a msgid to subscribe to (this may overlap real msgids) */
-        TestMsgId = CFE_SB_MSGID_WRAP_VALUE(CFE_PLATFORM_CMD_MID_BASE + NumSubs);
+        TestMsgId = CFE_SB_ValueToMsgId(CFE_PLATFORM_CMD_MID_BASE + NumSubs);
 
         Status = CFE_SB_Subscribe(TestMsgId, PipeId);
         if (Status != CFE_SUCCESS)
diff --git a/modules/cfe_testcase/src/tbl_information_test.c b/modules/cfe_testcase/src/tbl_information_test.c
index 813aa4ef0..bb44c31dc 100644
--- a/modules/cfe_testcase/src/tbl_information_test.c
+++ b/modules/cfe_testcase/src/tbl_information_test.c
@@ -78,7 +78,7 @@ void TestNotifyByMessage(void)
     UtPrintf("Testing: CFE_TBL_NotifyByMessage");
     CFE_TBL_Handle_t  SharedTblHandle;
     const char *      SharedTblName = "SAMPLE_APP.SampleAppTable";
-    CFE_SB_MsgId_t    TestMsgId     = CFE_TEST_CMD_MID;
+    CFE_SB_MsgId_t    TestMsgId     = CFE_SB_ValueToMsgId(CFE_TEST_CMD_MID);
     CFE_MSG_FcnCode_t TestCmdCode   = 0;
     uint32            TestParameter = 0;
 
diff --git a/modules/cfe_testcase/src/tbl_registration_test.c b/modules/cfe_testcase/src/tbl_registration_test.c
index ed300ece3..dcbf74885 100644
--- a/modules/cfe_testcase/src/tbl_registration_test.c
+++ b/modules/cfe_testcase/src/tbl_registration_test.c
@@ -220,7 +220,7 @@ void TestTblNonAppContext(void)
                       CFE_ES_ERR_RESOURCEID_NOT_VALID);
     UtAssert_INT32_EQ(CFE_TBL_Manage(CFE_FT_Global.TblHandle), CFE_ES_ERR_RESOURCEID_NOT_VALID);
     UtAssert_INT32_EQ(CFE_TBL_Modified(CFE_FT_Global.TblHandle), CFE_ES_ERR_RESOURCEID_NOT_VALID);
-    UtAssert_INT32_EQ(CFE_TBL_NotifyByMessage(CFE_FT_Global.TblHandle, CFE_TEST_CMD_MID, 0, 0),
+    UtAssert_INT32_EQ(CFE_TBL_NotifyByMessage(CFE_FT_Global.TblHandle, CFE_SB_ValueToMsgId(CFE_TEST_CMD_MID), 0, 0),
                       CFE_ES_ERR_RESOURCEID_NOT_VALID);
     UtAssert_INT32_EQ(CFE_TBL_ReleaseAddress(CFE_FT_Global.TblHandle), CFE_ES_ERR_RESOURCEID_NOT_VALID);
     UtAssert_INT32_EQ(CFE_TBL_Share(&Handle, CFE_FT_Global.TblName), CFE_ES_ERR_RESOURCEID_NOT_VALID);
diff --git a/modules/core_api/fsw/inc/cfe_sb.h b/modules/core_api/fsw/inc/cfe_sb.h
index 8f1eeff8f..0133eb06c 100644
--- a/modules/core_api/fsw/inc/cfe_sb.h
+++ b/modules/core_api/fsw/inc/cfe_sb.h
@@ -827,7 +827,7 @@ static inline CFE_SB_MsgId_Atom_t CFE_SB_MsgIdToValue(CFE_SB_MsgId_t MsgId)
  */
 static inline CFE_SB_MsgId_t CFE_SB_ValueToMsgId(CFE_SB_MsgId_Atom_t MsgIdValue)
 {
-    CFE_SB_MsgId_t Result = CFE_SB_MSGID_WRAP_VALUE(MsgIdValue);
+    CFE_SB_MsgId_t Result = CFE_SB_MSGID_C(MsgIdValue);
     return Result;
 }
 /** @} */
diff --git a/modules/core_api/fsw/inc/cfe_sb_api_typedefs.h b/modules/core_api/fsw/inc/cfe_sb_api_typedefs.h
index 64d800062..95a92fecc 100644
--- a/modules/core_api/fsw/inc/cfe_sb_api_typedefs.h
+++ b/modules/core_api/fsw/inc/cfe_sb_api_typedefs.h
@@ -63,7 +63,20 @@
  *
  * \sa CFE_SB_ValueToMsgId()
  */
-#define CFE_SB_MSGID_WRAP_VALUE(val) ((CFE_SB_MsgId_t)(val))
+#define CFE_SB_MSGID_WRAP_VALUE(val) (val)
+
+/**
+ * \brief Translation macro to convert to MsgId integer values from a literal
+ *
+ * This ensures that the literal is interpreted as the CFE_SB_MsgId_t type, rather
+ * than the default type associated with that literal (e.g. int/unsigned int).
+ *
+ * \note Due to constraints in C99 this style of initializer can only be used
+ * at runtime, not for static/compile-time initializers.
+ *
+ * \sa CFE_SB_ValueToMsgId()
+ */
+#define CFE_SB_MSGID_C(val) ((CFE_SB_MsgId_t)CFE_SB_MSGID_WRAP_VALUE(val))
 
 /**
  * \brief Translation macro to convert to MsgId integer values from opaque/abstract API values
@@ -96,7 +109,7 @@
  * purposes (rvalue), #CFE_SB_MSGID_RESERVED should be used instead.
  * However, in the current implementation, they are equivalent.
  */
-#define CFE_SB_INVALID_MSG_ID CFE_SB_MSGID_RESERVED
+#define CFE_SB_INVALID_MSG_ID CFE_SB_MSGID_C(-1)
 
 /**
  * \brief Cast/Convert a generic CFE_ResourceId_t to a CFE_SB_PipeId_t
diff --git a/modules/msg/ut-coverage/test_cfe_msg_msgid_v1.c b/modules/msg/ut-coverage/test_cfe_msg_msgid_v1.c
index b7616a27b..719805569 100644
--- a/modules/msg/ut-coverage/test_cfe_msg_msgid_v1.c
+++ b/modules/msg/ut-coverage/test_cfe_msg_msgid_v1.c
@@ -50,16 +50,17 @@ void Test_MSG_MsgId(void)
     UtAssert_INT32_EQ(CFE_MSG_SetMsgId(NULL, msgid), CFE_MSG_BAD_ARGUMENT);
     UtAssert_INT32_EQ(CFE_MSG_SetMsgId(&msg, CFE_SB_INVALID_MSG_ID), CFE_MSG_BAD_ARGUMENT);
     UtAssert_INT32_EQ(Test_MSG_NotZero(&msg), 0);
-    UtAssert_INT32_EQ(CFE_MSG_SetMsgId(&msg, CFE_PLATFORM_SB_HIGHEST_VALID_MSGID + 1), CFE_MSG_BAD_ARGUMENT);
+    UtAssert_INT32_EQ(CFE_MSG_SetMsgId(&msg, CFE_SB_ValueToMsgId(CFE_PLATFORM_SB_HIGHEST_VALID_MSGID + 1)),
+                      CFE_MSG_BAD_ARGUMENT);
     UtAssert_INT32_EQ(Test_MSG_NotZero(&msg), 0);
-    UtAssert_INT32_EQ(CFE_MSG_SetMsgId(&msg, 0xFFFF), CFE_MSG_BAD_ARGUMENT);
+    UtAssert_INT32_EQ(CFE_MSG_SetMsgId(&msg, CFE_SB_ValueToMsgId(0xFFFF)), CFE_MSG_BAD_ARGUMENT);
     UtAssert_INT32_EQ(Test_MSG_NotZero(&msg), 0);
 
     UtPrintf("Set msg to all F's, set msgid to 0 and verify");
     memset(&msg, 0xFF, sizeof(msg));
     CFE_UtAssert_SUCCESS(CFE_MSG_GetMsgId(&msg, &msgid));
     UtAssert_INT32_EQ(CFE_SB_MsgIdToValue(msgid), 0xFFFF);
-    CFE_UtAssert_SUCCESS(CFE_MSG_SetMsgId(&msg, 0));
+    CFE_UtAssert_SUCCESS(CFE_MSG_SetMsgId(&msg, CFE_SB_ValueToMsgId(0)));
     UT_DisplayPkt(&msg, sizeof(msg));
     CFE_UtAssert_SUCCESS(CFE_MSG_GetMsgId(&msg, &msgid));
     UtAssert_INT32_EQ(CFE_SB_MsgIdToValue(msgid), 0);
@@ -69,7 +70,7 @@ void Test_MSG_MsgId(void)
     memset(&msg, 0, sizeof(msg));
     CFE_UtAssert_SUCCESS(CFE_MSG_GetMsgId(&msg, &msgid));
     UtAssert_INT32_EQ(CFE_SB_MsgIdToValue(msgid), 0);
-    CFE_UtAssert_SUCCESS(CFE_MSG_SetMsgId(&msg, CFE_PLATFORM_SB_HIGHEST_VALID_MSGID));
+    CFE_UtAssert_SUCCESS(CFE_MSG_SetMsgId(&msg, CFE_SB_ValueToMsgId(CFE_PLATFORM_SB_HIGHEST_VALID_MSGID)));
     UT_DisplayPkt(&msg, sizeof(msg));
     CFE_UtAssert_SUCCESS(CFE_MSG_GetMsgId(&msg, &msgid));
     UtAssert_INT32_EQ(CFE_SB_MsgIdToValue(msgid), CFE_PLATFORM_SB_HIGHEST_VALID_MSGID);