diff --git a/apps/decoder.c b/apps/decoder.c
index be38d4e859da32cb390f9e92ef983885bad6a9aa..a5927d06e4adbe65cf9735f1e2a1420d00ba2a9a 100644
--- a/apps/decoder.c
+++ b/apps/decoder.c
@@ -1713,9 +1713,13 @@ static ivas_error initOnFirstGoodFrame(
         if ( arg.rtpOutSR && srRtp != NULL )
         {
             FILE *fParamsSR = NULL;
-            char srParamsFile[FILENAME_MAX], *ext = ".sr.txt";
-            strncpy( srParamsFile, arg.outputWavFilename, FILENAME_MAX - sizeof( ext ) );
-            strncat( srParamsFile, ext, sizeof( ext ) + 1 );
+            char srParamsFile[FILENAME_MAX];
+            const char *ext = ".sr.txt";
+
+            strncpy( srParamsFile, arg.outputWavFilename, FILENAME_MAX - strlen( ext ) - 1 );
+            srParamsFile[FILENAME_MAX - strlen( ext ) - 1] = '\0';
+            strncat( srParamsFile, ext, strlen( ext ) );
+            srParamsFile[FILENAME_MAX - 1] = '\0';
 
             /* Write the Split Rendering Params passed from SDP to srParamsFile */
             fParamsSR = fopen( srParamsFile, "w" );