diff --git a/parser.cpp b/parser.cpp
index 340267701..7ed65bc82 100644
--- a/parser.cpp
+++ b/parser.cpp
@@ -1012,6 +1012,10 @@ int parser_t::get_lineno() const
 
 const wchar_t *parser_t::current_filename() const
 {
+    /* We query a global array for the current file name, so it only makes sense to ask this on the principal parser. */
+    ASSERT_IS_MAIN_THREAD();
+    assert(this == &principal_parser());
+    
 	block_t *b = current_block;
 
 	while( 1 )
diff --git a/reader.cpp b/reader.cpp
index 10f020043..2e67c89f4 100644
--- a/reader.cpp
+++ b/reader.cpp
@@ -44,6 +44,7 @@ commence.
 #include <sys/poll.h>
 #include <unistd.h>
 #include <wctype.h>
+#include <stack>
 
 #if HAVE_NCURSES_H
 #include <ncurses.h>
@@ -103,6 +104,7 @@ commence.
 #include "halloc.h"
 #include "halloc_util.h"
 #include "iothread.h"
+#include "intern.h"
 
 #include "parse_util.h"
 
@@ -325,9 +327,9 @@ static int is_interactive_read;
 static int end_loop = 0;
 
 /**
-   The list containing names of files that are being parsed
+   The stack containing names of files that are being parsed
 */
-static array_list_t current_filename;
+static std::stack<const wchar_t *> current_filename;
 
 
 /**
@@ -498,21 +500,24 @@ void reader_handle_int( int sig )
 	
 }
 
-wchar_t *reader_current_filename()
+const wchar_t *reader_current_filename()
 {
-	return al_get_count( &current_filename )?(wchar_t *)al_peek( &current_filename ):0;
+    ASSERT_IS_MAIN_THREAD();
+    return current_filename.empty() ? NULL : current_filename.top();
 }
 
 
 void reader_push_current_filename( const wchar_t *fn )
 {
-	al_push( &current_filename, fn );
+    ASSERT_IS_MAIN_THREAD();
+    current_filename.push(intern(fn));
 }
 
 
-wchar_t *reader_pop_current_filename()
+void reader_pop_current_filename()
 {
-	return (wchar_t *)al_pop( &current_filename );
+    ASSERT_IS_MAIN_THREAD();
+	current_filename.pop();
 }
 
 
@@ -730,14 +735,11 @@ void reader_init()
 	shell_modes.c_lflag &= ~ECHO;     /* turn off echo mode */
     shell_modes.c_cc[VMIN]=1;
     shell_modes.c_cc[VTIME]=0;
-
-	al_init( &current_filename);
 }
 
 
 void reader_destroy()
 {
-	al_destroy( &current_filename);
 	tcsetattr(0, TCSANOW, &saved_modes);
 }
 
diff --git a/reader.h b/reader.h
index e9ac22799..593a816db 100644
--- a/reader.h
+++ b/reader.h
@@ -46,7 +46,7 @@ void reader_destroy();
 /**
    Returns the filename of the file currently read
 */
-wchar_t *reader_current_filename();
+const wchar_t *reader_current_filename();
 
 /**
    Push a new filename on the stack of read files
@@ -57,7 +57,7 @@ void reader_push_current_filename( const wchar_t *fn );
 /**
    Pop the current filename from the stack of read files
  */
-wchar_t *reader_pop_current_filename();
+void reader_pop_current_filename();
 
 /**
    Write the title to the titlebar. This function is called just