diff --git a/c02.c b/c02.c
index 8a7fab8..27c1935 100644
--- a/c02.c
+++ b/c02.c
@@ -45,6 +45,7 @@ void init()
   vrwrtn = FALSE;
   zpaddr = 0;
   invasc = FALSE;
+  mskasc = FALSE;
   fcase = FALSE;
 }
 
diff --git a/include.c b/include.c
index 7d45462..dc06739 100644
--- a/include.c
+++ b/include.c
@@ -75,9 +75,10 @@ void pdefin()
 void pascii()
 {
   getwrd(); //Get Pragma Subdirective
-  if (wordis("INVERT")) {
+  if (wordis("INVERT"))
     invasc = TRUE;
-  }
+  if (wordis("MASK"))
+    mskasc = TRUE;
   else {
     fprintf(stderr, "Unrecognized option '%s'\n", word);
     exterr(EXIT_FAILURE);
diff --git a/parse.c b/parse.c
index 0328529..9d02f97 100644
--- a/parse.c
+++ b/parse.c
@@ -36,6 +36,7 @@ int isxpre() {return TF(isvpre() || match('-'));}
 
 /* Conversion Functions */
 char invchr(char c) {return isalpha(c)?(islower(c)?toupper(c):tolower(c)):c;}
+char mskchr(char c) {return c | 0x80;}
 
 /* if Word is s then return TRUE else return FALSE*/
 int wordis(char *s)
@@ -268,6 +269,7 @@ int prschr()
   c = getnxt();
   DEBUG("Extracted character %c\n", c);
   if (invasc) c = invchr(c);
+  if (mskasc) c = mskchr(c);
   word[wrdlen++] = c;
   expect('\'');
   word[wrdlen++] = '\'';
diff --git a/parse.h b/parse.h
index 0df06e9..938ef7c 100644
--- a/parse.h
+++ b/parse.h
@@ -20,6 +20,7 @@ int  defcnt;                     //Number of Definitions Defined
 int  defidx;                     //Index into Definition Tables
 
 int invasc;                    //Invert ASCII Flag
+int mskasc;                    //Set High Bit Flag
 
 int match(char c);             //Does Next Character match c
 int isalph();                  //Is Next Character Alphabetic