diff --git a/src/pl/plpython/plpython.c b/src/pl/plpython/plpython.c
index 9352580..b2333b8 100644
*** a/src/pl/plpython/plpython.c
--- b/src/pl/plpython/plpython.c
*************** get_source_line(const char *src, int lin
*** 4507,4512 ****
--- 4507,4520 ----
  	if (next == NULL)
  		return pstrdup(s);
  
+ 	/*
+ 	 * Sanity check, next < s if the line was all-whitespace, which should
+ 	 * never happen if Python reported an frame created on that line, but
+ 	 * check anyway.
+ 	 */
+ 	if (next < s)
+ 		return NULL;
+ 
  	return pnstrdup(s, next - s);
  }
  
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4603,4608 ****
--- 4611,4617 ----
  		PyObject	*volatile code = NULL;
  		PyObject	*volatile name = NULL;
  		PyObject	*volatile lineno = NULL;
+ 		PyObject	*volatile filename = NULL;
  
  		PG_TRY();
  		{
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4621,4626 ****
--- 4630,4639 ----
  			name = PyObject_GetAttrString(code, "co_name");
  			if (name == NULL)
  				elog(ERROR, "could not get function name from Python code object");
+ 
+ 			filename = PyObject_GetAttrString(code, "co_filename");
+ 			if (filename == NULL)
+ 				elog(ERROR, "could not get file name from Python code object");
  		}
  		PG_CATCH();
  		{
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4628,4633 ****
--- 4641,4647 ----
  			Py_XDECREF(code);
  			Py_XDECREF(name);
  			Py_XDECREF(lineno);
+ 			Py_XDECREF(filename);
  			PG_RE_THROW();
  		}
  		PG_END_TRY();
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4638,4643 ****
--- 4652,4658 ----
  			char	*proname;
  			char	*fname;
  			char	*line;
+ 			char	*plain_filename;
  			long	plain_lineno;
  
  			/*
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4651,4656 ****
--- 4666,4672 ----
  				fname = PyString_AsString(name);
  
  			proname = PLy_procedure_name(PLy_curr_procedure);
+ 			plain_filename = PyString_AsString(filename);
  			plain_lineno = PyInt_AsLong(lineno);
  
  			if (proname == NULL)
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4662,4668 ****
  					&tbstr, "\n  PL/Python function \"%s\", line %ld, in %s",
  					proname, plain_lineno - 1, fname);
  
! 			if (PLy_curr_procedure)
  			{
  				/*
  				 * If we know the current procedure, append the exact
--- 4678,4686 ----
  					&tbstr, "\n  PL/Python function \"%s\", line %ld, in %s",
  					proname, plain_lineno - 1, fname);
  
! 			/* the code object was compiled with "<string>" as the filename */
! 			if (PLy_curr_procedure && plain_filename != NULL &&
! 				strcmp(plain_filename, "<string>") == 0)
  			{
  				/*
  				 * If we know the current procedure, append the exact
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4670,4676 ****
  				 * traceback.py module behavior.  We could store the
  				 * already line-split source to avoid splitting it
  				 * every time, but producing a traceback is not the
! 				 * most important scenario to optimize for.
  				 */
  				line = get_source_line(PLy_curr_procedure->src, plain_lineno);
  				if (line)
--- 4688,4696 ----
  				 * traceback.py module behavior.  We could store the
  				 * already line-split source to avoid splitting it
  				 * every time, but producing a traceback is not the
! 				 * most important scenario to optimize for.  However,
! 				 * do not go as far as traceback.py in reading the source
! 				 * of imported modules.
  				 */
  				line = get_source_line(PLy_curr_procedure->src, plain_lineno);
  				if (line)
*************** PLy_traceback(char **xmsg, char **tbmsg,
*** 4685,4690 ****
--- 4705,4711 ----
  		Py_DECREF(code);
  		Py_DECREF(name);
  		Py_DECREF(lineno);
+ 		Py_DECREF(filename);
  
  		/* Release the current frame and go to the next one. */
  		tb_prev = tb;