Index: src/driver/as.cc
===================================================================
--- src/driver/as.cc	(revision 0a76d8456d64af211f4ff09a58e7800b23b143d9)
+++ src/driver/as.cc	(revision f7ac09db66c129f692946799a998876f7b6df2b5)
@@ -10,6 +10,6 @@
 // Created On       : Wed Aug  1 10:49:42 2018
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Thu Aug  2 16:18:14 2018
-// Update Count     : 84
+// Last Modified On : Thu Aug  2 17:50:09 2018
+// Update Count     : 90
 // 
 
@@ -38,20 +38,25 @@
 	off_t size = mystat.st_size;
 
-	if ( ftruncate( fd, size + 1 ) ) { perror( "ftruncate" ); exit( EXIT_FAILURE ); };
-
 	char * start = (char *)mmap( NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 );
 	if ( start == (void *)-1 ) { perror( "mmap" ); exit( EXIT_FAILURE ); };
 
-	char * cursor = strstr( start, ".Ldebug_info0:" );	// debug information ?
-	for ( int i = 0; i < 8; i += 1 ) {					// move N (magic) lines forward
-		cursor = strstr( cursor, "\n" ) + 1;
-	} // for
-	cursor -= 2;										// backup over "c\n" language value
-	if ( *(cursor - 1) != 'x' ) { fprintf( stderr, "invalid C language code\n" ); exit( EXIT_FAILURE ); };
-	memmove( cursor + 2, cursor + 1, start + size - cursor - 1 ); // move text 1 character right
-	*(cursor) = '2';									// replace with CFA language value
-	*(cursor + 1) = '5';
+	if ( char * cursor = strstr( start, ".Ldebug_info0:" ) ) { // debug information ?
+		// Expand file by one byte to hold 2 character Cforall language code.
+		if ( ftruncate( fd, size + 1 ) ) { perror( "ftruncate" ); exit( EXIT_FAILURE ); };
 
-	if ( munmap( start, size ) ) { perror( "munmap" ); exit( EXIT_FAILURE ); };
+		for ( int i = 0; i < 8; i += 1 ) {				// move N (magic) lines forward
+			cursor = strstr( cursor, "\n" ) + 1;
+		} // for
+
+		cursor -= 2;									// backup over "c\n" language value
+		if ( *(cursor - 1) != 'x' ) { fprintf( stderr, "invalid C language code\n" ); exit( EXIT_FAILURE ); };
+
+		memmove( cursor + 2, cursor + 1, start + size - cursor - 1 ); // move remaining text 1 character right
+
+		*(cursor) = '2';								// replace C language value with CFA
+		*(cursor + 1) = '5';
+	} // if
+
+	if ( munmap( start, size ) ) { perror( "munmap" ); exit( EXIT_FAILURE ); }; // update on disk
 
 	argv[0] = "as";