diff --git a/modules/core_private/ut-stubs/src/ut_support.c b/modules/core_private/ut-stubs/src/ut_support.c
index edc7c8533..5f50655fa 100644
--- a/modules/core_private/ut-stubs/src/ut_support.c
+++ b/modules/core_private/ut-stubs/src/ut_support.c
@@ -654,7 +654,7 @@ bool CFE_UtAssert_MessageCheck_Impl(bool Status, const char *File, uint32 Line,
 
     /* Locate the actual end of the string, but limited to length of local buffer */
     /* Reserve two extra chars for quotes */
-    EndPtr = memchr(FormatString, 0, sizeof(ScrubbedFormat) - 2);
+    EndPtr = memchr(FormatString, 0, sizeof(ScrubbedFormat) - 3);
     if (EndPtr != NULL)
     {
         FormatLen = EndPtr - FormatString;
@@ -674,8 +674,8 @@ bool CFE_UtAssert_MessageCheck_Impl(bool Status, const char *File, uint32 Line,
     /* Need to make a copy, as the input string is "const" */
     ScrubbedFormat[0] = '\'';
     memcpy(&ScrubbedFormat[1], FormatString, FormatLen);
-    ScrubbedFormat[FormatLen]     = '\'';
-    ScrubbedFormat[FormatLen + 1] = 0;
+    ScrubbedFormat[FormatLen + 1] = '\'';
+    ScrubbedFormat[FormatLen + 2] = 0;
 
     return UtAssert_GenericSignedCompare(Status, UtAssert_Compare_GT, 0, UtAssert_Radix_DECIMAL, File, Line, Desc,
                                          ScrubbedFormat, "");