--- c/util/osu_util.c.orig	2025-12-17 12:15:21
+++ c/util/osu_util.c	2026-06-16 15:25:02
@@ -1478,21 +1478,25 @@
 
                 break;
             case 'T':
-                if (0 == strncasecmp(optarg, "MPI_CHAR", 8)) {
+                if (0 == strcasecmp(optarg, "MPI_CHAR")) {
                     options.omb_dtype_list[options.omb_dtype_itr++] = OMB_CHAR;
-                } else if (0 == strncasecmp(optarg, "MPI_INT", 7)) {
+                } else if (0 == strcasecmp(optarg, "MPI_INT")) {
                     options.omb_dtype_list[options.omb_dtype_itr++] = OMB_INT;
-                } else if (0 == strncasecmp(optarg, "MPI_FLOAT", 9)) {
+                } else if (0 == strcasecmp(optarg, "MPI_FLOAT")) {
                     options.omb_dtype_list[options.omb_dtype_itr++] = OMB_FLOAT;
-                } else if (0 == strncasecmp(optarg, "MPI_DOUBLE", 10)) {
+                } else if (0 == strcasecmp(optarg, "MPI_DOUBLE")) {
                     options.omb_dtype_list[options.omb_dtype_itr++] =
                         OMB_DOUBLE;
-                } else if (0 == strncasecmp(optarg, "ALL", 3)) {
+                } else if (0 == strcasecmp(optarg, "ALL")) {
                     options.omb_dtype_list[options.omb_dtype_itr++] = OMB_CHAR;
                     options.omb_dtype_list[options.omb_dtype_itr++] = OMB_INT;
                     options.omb_dtype_list[options.omb_dtype_itr++] = OMB_FLOAT;
                     options.omb_dtype_list[options.omb_dtype_itr++] =
                         OMB_DOUBLE;
+                } else {
+                    bad_usage.message = "Unsupported MPI datatype specified";
+                    bad_usage.optarg = optarg;
+                    return PO_BAD_USAGE;
                 }
                 break;
             case 'I':