diff --git a/src/tools/training_data_generator.cpp b/src/tools/training_data_generator.cpp
index 746de279..a8804fef 100644
--- a/src/tools/training_data_generator.cpp
+++ b/src/tools/training_data_generator.cpp
@@ -896,7 +896,10 @@ namespace Stockfish::Tools
                 params.ensure_quiet = true;
             }
             else
-                cout << "ERROR: Ignoring unknown option " << token << endl;
+            {
+                cout << "ERROR: Unknown option " << token << ". Exiting...\n";
+                return;
+            }
         }
 
         if (!sfen_format.empty())
diff --git a/src/tools/training_data_generator_nonpv.cpp b/src/tools/training_data_generator_nonpv.cpp
index 3db95033..e8df9c50 100644
--- a/src/tools/training_data_generator_nonpv.cpp
+++ b/src/tools/training_data_generator_nonpv.cpp
@@ -443,7 +443,10 @@ namespace Stockfish::Tools
                 UCI::setoption("EnableTranspositionTable", "true");
             }
             else
-                cout << "ERROR: Ignoring unknown option " << token << endl;
+            {
+                cout << "ERROR: Unknown option " << token << ". Exiting...\n";
+                return;
+            }
         }
 
         if (!sfen_format.empty())
diff --git a/src/tools/transform.cpp b/src/tools/transform.cpp
index 0b7f5a27..ab7a3db8 100644
--- a/src/tools/transform.cpp
+++ b/src/tools/transform.cpp
@@ -210,6 +210,11 @@ namespace Stockfish::Tools
                 is >> params.input_filename;
             else if (token == "output_file")
                 is >> params.output_filename;
+            else
+            {
+                std::cout << "ERROR: Unknown option " << token << ". Exiting...\n";
+                return;
+            }
         }
 
         std::cout << "Performing transform nudged_static with parameters:\n";
@@ -474,6 +479,11 @@ namespace Stockfish::Tools
                 is >> params.keep_moves;
             else if (token == "research_count")
                 is >> params.research_count;
+            else
+            {
+                std::cout << "ERROR: Unknown option " << token << ". Exiting...\n";
+                return;
+            }
         }
 
         params.enforce_constraints();