diff --git a/interpreter.cpp b/interpreter.cpp
index 1b1b71f..4f3615c 100644
--- a/interpreter.cpp
+++ b/interpreter.cpp
@@ -52,7 +52,7 @@ std::string interpreter::eval(std::istream& in, bool& done) {
             _pc++;
             continue;
         }
-
+        
         // check literal int
         if (std::isdigit(code[0])) {
             _stack.push_back(code);
@@ -130,7 +130,7 @@ void interpreter::exec_instruction(const std::string& code, bool& done) {
     else if (code == "inp") inp();
     else if (code == "out") out();
     else if (code == "err") err();
-    else throw syntax_error {code};
+    else throw syntax_error {code, _pc + 1};
 }
 
 // integer operations -----------------------------------------------------
diff --git a/interpreter.hpp b/interpreter.hpp
index c5b5f77..01a3abd 100644
--- a/interpreter.hpp
+++ b/interpreter.hpp
@@ -18,7 +18,11 @@
 
 class syntax_error : public std::runtime_error {
     public:
-        syntax_error(const std::string& what_arg) : std::runtime_error(what_arg) {}
+        syntax_error(const std::string& what_arg, size_t lineno)
+            : std::runtime_error {what_arg}, _lineno {lineno} {}
+        size_t lineno() const { return _lineno; }
+    private:
+        size_t _lineno {0};
 };
 
 class interpreter {