diff --git a/applications/Parser/src/main.cpp b/applications/Parser/src/main.cpp
index 6a05319..84c670a 100644
--- a/applications/Parser/src/main.cpp
+++ b/applications/Parser/src/main.cpp
@@ -1,4 +1,4 @@
-// Copyright 2019 - University of Strathclyde, King's College London and Schlumberger Ltd
+// Copyright 2019-2025 - University of Strathclyde, King's College London, Schlumberger Ltd and SIFT, LLC
 // This source code is licensed under the BSD license found in the LICENSE file in the root directory of this source tree.
 
 #include "FlexLexer.h"
@@ -10,6 +10,10 @@
 extern int yyparse();
 extern int yydebug;
 
+void usage();
+
+static bool failOnBadInput = 0;
+
 using std::ifstream;
 using std::ofstream;
 
@@ -39,8 +43,24 @@ int main(int argc, char *argv[]) {
 
   yfl = new yyFlexLexer;
 
+  int argcount = 1;
+
+  // Parse command line options (extensible)
+  while (argcount < argc && argv[argcount][0] == '-') {
+    switch (argv[argcount][1]) {
+    case 'x':
+      failOnBadInput = true;
+      ++argcount;
+      break;
+    default:
+      cout << "Unknown option: " << argv[argcount] << "\n";
+      usage();
+      exit(1);
+    }
+  }
+
   // Loop over given args
-  for (int a = 1; a < argc; ++a) {
+  for (int a = argcount; a < argc; ++a) {
     current_filename = argv[a];
     cout << "File: " << current_filename << '\n';
     current_in_stream = new ifstream(current_filename);
@@ -66,4 +86,20 @@ int main(int argc, char *argv[]) {
   // Output the errors from all input files
   current_analysis->error_list.report();
   delete yfl;
+  if (failOnBadInput && current_analysis->error_list.errors > 0) {
+    return 1;
+    }
+  return 0;
 }
+
+
+void usage() {
+  cout << "Parser: The PDDL+ plan parsing tool\n"
+       << "Version 4: Validates continuous effects, events and processes.\n"
+       << "\nAuthors: Derek Long, Richard Howey, Stephen Cresswell and Maria "
+          "Fox\n"
+       << "https:://github.com/KCL-Planning/VAL\n\n"
+       << "Usage: Parser [options] domainFile problemFile planFile1 ...\n"
+       << "Options:\n"
+       << "    -x         -- Fail with non-zero exit code if the input fails to parse.\n";
+};
diff --git a/applications/Validate/src/main.cpp b/applications/Validate/src/main.cpp
index 428acaf..70e1f05 100644
--- a/applications/Validate/src/main.cpp
+++ b/applications/Validate/src/main.cpp
@@ -33,6 +33,8 @@ extern int yydebug;
 
 extern char *current_filename;
 
+static bool failOnBadPlan = 0;
+
 namespace VAL {
 
   extern parse_category *top_thing;
@@ -80,6 +82,7 @@ void usage() {
        << "    -j         -- When varying the values of PNEs also vary for "
           "event preconditions. (default = false)\n"
        << "    -v         -- Verbose reporting of plan check progress.\n"
+       << "    -x         -- Fail with non-zero exit code on validation failures.\n"
        << "    -l         -- Verbose LaTeX reporting of plan check progress.\n"
        << "    -a         -- Do not output plan repair advice when Verbose is "
           "on.\n"
@@ -125,7 +128,11 @@ plan *getPlan(int &argc, char *argv[], int &argcount, TypeChecker &tc,
     failed.push_back(name);
     *report << "Bad plan file!\n";
     the_plan = 0;
-    return the_plan;
+    if ( failOnBadPlan ) {
+      exit(1);
+    } else {
+      return the_plan;
+    }
   };
 
   yfl = new yyFlexLexer(&planFile, &cout);
@@ -141,7 +148,11 @@ plan *getPlan(int &argc, char *argv[], int &argcount, TypeChecker &tc,
     if (Silent > 1) *report << "failed\n";
     delete the_plan;
     the_plan = 0;
-    return the_plan;
+    if ( failOnBadPlan ) {
+      exit(1);
+    } else {
+      return the_plan;
+    }
   };
 
   if (the_plan->getTime() >= 0) {
@@ -502,7 +513,7 @@ int main(int argc, char *argv[]) {
   try {
     if (argc < 2) {
       usage();
-      return 0;
+      return 1;
     };
 
     current_analysis = &an_analysis;
@@ -708,6 +719,10 @@ int main(int argc, char *argv[]) {
           giveAdvice = false;
           ++argcount;
           break;
+        case 'x':
+          failOnBadPlan = true;
+          ++argcount;
+          break;
         case 'f': {
           LaTeX = true;
           Verbose = true;
@@ -777,6 +792,8 @@ int main(int argc, char *argv[]) {
       exit(-1);
     };
 
+    // I believe this means that there is only one argument, and it's
+    // been processed successfully.
     if (argcount >= argc) {
       return 0;
     };