diff --git a/src/eql.cpp b/src/eql.cpp
index 0213a63..7a551cb 100644
--- a/src/eql.cpp
+++ b/src/eql.cpp
@@ -7,6 +7,7 @@
 #include <QApplication>
 #include <QTimer>
 #include <QStringList>
+#include <QDebug>
 
 const char EQL::version[] = "20.7.1"; // July 2020
 
@@ -54,9 +55,22 @@ void EQL::ini(int argc, char** argv) {
     cl_booted = true;
     cl_boot(argc, argv); }
 
-void EQL::eval(const char* lisp_code) {
+void EQL::eval(const char* lisp_code, const EvalMode mode) {
     CL_CATCH_ALL_BEGIN(ecl_process_env()) {
-        si_safe_eval(2, ecl_read_from_cstring((char*)lisp_code), Cnil); }
+        switch(mode) {
+            case DebugOnError:
+                si_safe_eval(2, ecl_read_from_cstring((char*)lisp_code), Cnil);
+                break;
+            case LogOnError:
+            case DieOnError:
+                cl_object ret = si_safe_eval(3, ecl_read_from_cstring((char*)lisp_code), Cnil, ecl_make_fixnum(EVAL_ERROR_VALUE));
+                if (ecl_t_of(ret) == t_fixnum && fix(ret) == EVAL_ERROR_VALUE) {
+                    qDebug()<<"Error evaluating " <<lisp_code;
+                    if (mode == DieOnError)
+                        exit(-1);
+                }
+        }
+    }
     CL_CATCH_ALL_END; }
 
 void EQL::ignoreIOStreams() {
@@ -74,6 +88,9 @@ void EQL::exec(const QStringList& args) {
         arguments.removeAll("-norc"); }
     else {
         eval("(x:when-it (probe-file \"~/.eclrc\") (load x:it))"); }
+    if (arguments.contains("-debug-on-error")) {
+        arguments.removeAll("-debug-on-error");
+        evalMode = DebugOnError; }
     // Slime
     int i_swank = arguments.indexOf(QRegExp("*start-swank*.lisp", Qt::CaseInsensitive, QRegExp::Wildcard));
     if(arguments.contains("-slime") || (i_swank != -1))  {
@@ -193,6 +210,7 @@ void EQL::runOnUiThread(void* function_or_closure) {
         CL_UNWIND_PROTECT_END; }
     CL_CATCH_ALL_END; }
 
+EQL::EvalMode EQL::evalMode = DieOnError;
 bool EQL::cl_booted = false;
 bool EQL::return_value_p = false;
 bool EQL::qexec = true;
diff --git a/src/eql5/eql.h b/src/eql5/eql.h
index 00381da..636d63c 100644
--- a/src/eql5/eql.h
+++ b/src/eql5/eql.h
@@ -17,6 +17,7 @@ QT_BEGIN_NAMESPACE
 
 #define QSLOT(x)   "1"#x
 #define QSIGNAL(x) "2"#x
+#define EVAL_ERROR_VALUE -1
 
 typedef void (*lisp_ini)(cl_object);
 
@@ -25,6 +26,12 @@ class EQL_EXPORT EQL : public QObject {
 public:
     EQL();
 
+    enum EvalMode {
+        DebugOnError,
+        LogOnError,
+        DieOnError,
+    };
+
     static bool cl_booted;
     static bool return_value_p;
     static bool qexec;
@@ -32,7 +39,8 @@ public:
     static QEventLoop* eventLoop;
     static void ini(int, char**);
     static void ini(char**);
-    static void eval(const char*);
+    static void eval(const char*, const EvalMode = evalMode);
+    static EvalMode evalMode;
 
     void exec(const QStringList&);
     void exec(lisp_ini, const QByteArray& = "nil", const QByteArray& = "eql-user"); // see my_app example
diff --git a/src/main.cpp b/src/main.cpp
index bc8771a..b0bd7f1 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -61,7 +61,7 @@ int main(int argc, char** argv) {
     QApplication qapp(argc, argv);
     QStringList args(QCoreApplication::arguments());
     if(args.contains("-h") || (args.contains("--help"))) {
-        std::cout << "Usage: eql5 [file] [-qtpl] [-qgui] [-quic file.ui [:ui-package] [:maximized]] [-slime] [-norc]" << std::endl;
+        std::cout << "Usage: eql5 [file] [-qtpl] [-qgui] [-quic file.ui [:ui-package] [:maximized]] [-slime] [-norc] [-debug-on-error]" << std::endl;
         exit(0); }
     ini();