diff --git a/src/cli.cpp b/src/cli.cpp
index e150e61..0592486 100644
--- a/src/cli.cpp
+++ b/src/cli.cpp
@@ -220,6 +220,12 @@ int CLI::validateCommandLine(Options* options, char *argv[], json *keys) {
     int intBinkID;
     sscanf(options->binkid.c_str(), "%x", &intBinkID);
 
+    // FE and FF are BINK 1998, but do not generate valid keys, so we throw an error
+    if (intBinkID >= 0xFE) {
+        fmt::print("ERROR: Terminal Services BINKs (FE and FF) are unsupported at this time\n");
+        return 1;
+    }
+    
     if (intBinkID >= 0x40) {
         // set bink2002 validate mode if in bink1998 validate mode, else set bink2002 generate mode
         options->applicationMode = (options->applicationMode == MODE_BINK1998_VALIDATE) ? MODE_BINK2002_VALIDATE : MODE_BINK2002_GENERATE;