diff --git a/src/basic/math_consts/bf11.const_HALF.s b/src/basic/math_consts/bf11.const_HALF.s
index a9ae49f1..ea23616c 100644
--- a/src/basic/math_consts/bf11.const_HALF.s
+++ b/src/basic/math_consts/bf11.const_HALF.s
@@ -3,8 +3,13 @@
 ;; #LAYOUT# *   BASIC_0 #TAKE
 ;; #LAYOUT# *   *       #IGNORE
 
+; This file is under the MIT license, it contains code released by Microsoft Corporation.
+; See LICENSE for more information.
+
+; Math package - the constant 1/2
+;
+; This is verified to be identical to the original Microsoft implementation where it was named FHALF
 ;
-; Math package - a constant, for documentation see:
 ; - https://www.c64-wiki.com/wiki/BASIC-ROM
 ; - Computes Mapping the Commodore 64, page 116
 ;
diff --git a/tools/similarity.c b/tools/similarity.c
index be5e9bc4..ef5612e1 100644
--- a/tools/similarity.c
+++ b/tools/similarity.c
@@ -20,7 +20,7 @@ int matches[MAX_SIZE];
 
 int phase_mask[MAX_SIZE+MAX_SIZE];
 
-#define NUM_CHUNKS 7
+#define NUM_CHUNKS 8
 // Pairs of start, end memory addresses of known exact similarity with the open source Microsoft BASIC
 unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xB391, 0xB39D,
@@ -29,6 +29,7 @@ unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xB983, 0xB9BB,
     0xBA28, 0xBCF2,
     0xBD7E, 0xBD90,
+    0xBF11, 0xBF15,
     0xBFB4, 0xBFBE,
 };