diff --git a/fsw/src/cf_cfdp.c b/fsw/src/cf_cfdp.c
index c79fa8d3..7e4c0376 100644
--- a/fsw/src/cf_cfdp.c
+++ b/fsw/src/cf_cfdp.c
@@ -299,22 +299,6 @@ CF_Logical_PduBuffer_t *CF_CFDP_ConstructPduHeader(const CF_Transaction_t *txn,
     return ph;
 }
 
-/*----------------------------------------------------------------
- *
- * Internal helper routine only, not part of API.
- *
- *-----------------------------------------------------------------*/
-static inline size_t CF_strnlen(const char *str, size_t maxlen)
-{
-    const char *end = memchr(str, 0, maxlen);
-    if (end != NULL)
-    {
-        /* actual length of string is difference */
-        maxlen = end - str;
-    }
-    return maxlen;
-}
-
 /*----------------------------------------------------------------
  *
  * Application-scope internal function
diff --git a/fsw/src/cf_utils.c b/fsw/src/cf_utils.c
index 4b35c9b6..715dd4de 100644
--- a/fsw/src/cf_utils.c
+++ b/fsw/src/cf_utils.c
@@ -196,8 +196,7 @@ CFE_Status_t CF_WriteHistoryEntryToFile(osal_id_t fd, const CF_History_t *histor
                 snprintf(linebuf, sizeof(linebuf), "DST: %s\n", history->fnames.dst_filename);
                 break;
         }
-
-        len = strlen(linebuf);
+        len = CF_strnlen(linebuf, (CF_FILENAME_MAX_LEN * 2) + 128);
         ret = CF_WrappedWrite(fd, linebuf, len);
         if (ret != len)
         {
@@ -588,3 +587,22 @@ CF_TxnStatus_t CF_TxnStatus_From_ConditionCode(CF_CFDP_ConditionCode_t cc)
     /* All CFDP CC values directly correspond to a Transaction Status of the same numeric value */
     return (CF_TxnStatus_t)cc;
 }
+
+/*----------------------------------------------------------------
+ *
+ * Function: CF_strnlen
+ *
+ * Application-scope internal function
+ * See description in cf_utils.h for argument/return detail
+ *
+ *-----------------------------------------------------------------*/
+size_t CF_strnlen(const char *str, size_t maxlen)
+{
+    const char *end = memchr(str, 0, maxlen);
+    if (end != NULL)
+    {
+        /* actual length of string is difference */
+        maxlen = end - str;
+    }
+    return maxlen;
+}
\ No newline at end of file
diff --git a/fsw/src/cf_utils.h b/fsw/src/cf_utils.h
index fd839ce0..81f833fd 100644
--- a/fsw/src/cf_utils.h
+++ b/fsw/src/cf_utils.h
@@ -518,4 +518,21 @@ CF_TxnStatus_t CF_TxnStatus_From_ConditionCode(CF_CFDP_ConditionCode_t cc);
  */
 bool CF_TxnStatus_IsError(CF_TxnStatus_t txn_stat);
 
+/************************************************************************/
+/** @brief Calculates the length of a string up to a maximum length
+ *
+ * Purpose: Provides a local OSAL routine to get the functionality
+ *          of the (non-C99) "strnlen()" function, via the
+ *          C89/C99 standard "memchr()" function instead.
+ *
+ * @par Assumptions, External Events, and Notes:
+ *       None
+ *
+ * @param str     Pointer to the input string
+ * @param maxlen  Maximum number of characters to check
+ *
+ * @returns Length of the string up to `maxlen` characters
+ */
+size_t CF_strnlen(const char *str, size_t maxlen);
+
 #endif /* !CF_UTILS_H */
diff --git a/unit-test/cf_utils_tests.c b/unit-test/cf_utils_tests.c
index 41010c91..7a4ae711 100644
--- a/unit-test/cf_utils_tests.c
+++ b/unit-test/cf_utils_tests.c
@@ -1142,6 +1142,37 @@ void Test_CF_TxnStatus_From_ConditionCode(void)
     }
 }
 
+/*******************************************************************************
+**
+**  CF_strnlen tests
+**
+*******************************************************************************/
+void Test_CF_strnlen_null_character_found(void)
+{
+    /* Arrange */
+    size_t result;
+    const char str[]  = "str";
+
+    /* Act */
+    result = CF_strnlen(str, sizeof(str));
+
+    /* Assert */
+    UtAssert_INT32_EQ(result, 3);
+}
+
+void Test_CF_strnlen_null_character_not_found(void)
+{
+    /* Arrange */
+    size_t result;
+    const char str[]  = "str";
+
+    /* Act */
+    result = CF_strnlen(str, sizeof(str) - 1);
+
+    /* Assert */
+    UtAssert_INT32_EQ(result, 3);
+}
+
 /*******************************************************************************
 **
 **  cf_utils_tests UtTest_Add groups
@@ -1291,6 +1322,13 @@ void add_CF_WrappedLseek_tests(void)
                cf_utils_tests_Teardown, "Test_CF_WrappedLseek_Call_OS_lseek_WithGivenArgumentsAndReturnItsReturnValue");
 }
 
+void add_CF_strnlen_tests(void)
+{
+    UtTest_Add(Test_CF_strnlen_null_character_found, cf_utils_tests_Setup,
+               cf_utils_tests_Teardown, "Test_CF_strnlen_null_character_found");
+    UtTest_Add(Test_CF_strnlen_null_character_not_found, cf_utils_tests_Setup,
+               cf_utils_tests_Teardown, "Test_CF_strnlen_null_character_not_found");
+}
 /*******************************************************************************
 **
 **  cf_utils_tests UtTest_Setup
@@ -1330,4 +1368,6 @@ void UtTest_Setup(void)
     add_CF_WrappedWrite_tests();
 
     add_CF_WrappedLseek_tests();
+
+    add_CF_strnlen_tests();
 }
diff --git a/unit-test/stubs/cf_utils_stubs.c b/unit-test/stubs/cf_utils_stubs.c
index bf36813b..09514b2f 100644
--- a/unit-test/stubs/cf_utils_stubs.c
+++ b/unit-test/stubs/cf_utils_stubs.c
@@ -41,7 +41,7 @@ void UT_DefaultHandler_CF_WriteTxnQueueDataToFile(void *, UT_EntryKey_t, const U
  * Generated stub function for CF_FindTransactionBySequenceNumber()
  * ----------------------------------------------------
  */
-CF_Transaction_t *CF_FindTransactionBySequenceNumber(CF_Channel_t       *chan,
+CF_Transaction_t *CF_FindTransactionBySequenceNumber(CF_Channel_t *      chan,
                                                      CF_TransactionSeq_t transaction_sequence_number,
                                                      CF_EntityId_t       src_eid)
 {
@@ -416,3 +416,20 @@ CFE_Status_t CF_WriteTxnQueueDataToFile(osal_id_t fd, CF_Channel_t *chan, CF_Que
 
     return UT_GenStub_GetReturnValue(CF_WriteTxnQueueDataToFile, CFE_Status_t);
 }
+
+/*
+ * ----------------------------------------------------
+ * Generated stub function for CF_strnlen()
+ * ----------------------------------------------------
+ */
+size_t CF_strnlen(const char *str, size_t maxlen)
+{
+    UT_GenStub_SetupReturnBuffer(CF_strnlen, size_t);
+
+    UT_GenStub_AddParam(CF_strnlen, const char *, str);
+    UT_GenStub_AddParam(CF_strnlen, size_t, maxlen);
+
+    UT_GenStub_Execute(CF_strnlen, Basic, NULL);
+
+    return UT_GenStub_GetReturnValue(CF_strnlen, size_t);
+}