diff --git a/src/basic/math_consts/b9bc.const_ONE.s b/src/basic/math_consts/b9bc.const_ONE.s
index 9c044036..27c298a6 100644
--- a/src/basic/math_consts/b9bc.const_ONE.s
+++ b/src/basic/math_consts/b9bc.const_ONE.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 - a constant, for documentation see:
+;
+; This is verified to be identical to the original Microsoft implementation where it was named FONE
+;
 ; - https://www.c64-wiki.com/wiki/BASIC-ROM
 ; - Computes Mapping the Commodore 64, page 113
 ;
diff --git a/tools/similarity.c b/tools/similarity.c
index 8fabb438..51bd6f0f 100644
--- a/tools/similarity.c
+++ b/tools/similarity.c
@@ -20,14 +20,13 @@ int matches[MAX_SIZE];
 
 int phase_mask[MAX_SIZE+MAX_SIZE];
 
-#define NUM_CHUNKS 10
+#define NUM_CHUNKS 9
 // 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,
     0xB3A2, 0xB3A5,
     0xB849, 0xB97D,
-    0xB983, 0xB9BB,
-    0xB9C1, 0xB9D5,
+    0xB983, 0xB9D5,
     0xBA28, 0xBCF2,
     0xBD7E, 0xBD90,
     0xBDB3, 0xBDC1,