diff --git a/diff.c b/diff.c
index a74e701806..74261b332a 100644
--- a/diff.c
+++ b/diff.c
@@ -801,16 +801,19 @@ enum diff_symbol {
 	DIFF_SYMBOL_CONTEXT_MARKER,
 	DIFF_SYMBOL_SEPARATOR
 };
+
 /*
  * Flags for content lines:
- * 0..12 are whitespace rules
- * 13-15 are WSEH_NEW | WSEH_OLD | WSEH_CONTEXT
+ * 0..11 are whitespace rules (see ws.h)
+ * 12..14 are WSEH_NEW | WSEH_CONTEXT | WSEH_OLD
  * 16 is marking if the line is blank at EOF
+ * 17..19 are used for color-moved.
  */
 #define DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF	(1<<16)
 #define DIFF_SYMBOL_MOVED_LINE			(1<<17)
 #define DIFF_SYMBOL_MOVED_LINE_ALT		(1<<18)
 #define DIFF_SYMBOL_MOVED_LINE_UNINTERESTING	(1<<19)
+
 #define DIFF_SYMBOL_CONTENT_WS_MASK (WSEH_NEW | WSEH_OLD | WSEH_CONTEXT | WS_RULE_MASK)
 
 /*
diff --git a/diff.h b/diff.h
index 2fa256c3ef..cbd355cf50 100644
--- a/diff.h
+++ b/diff.h
@@ -331,9 +331,9 @@ struct diff_options {
 
 	int ita_invisible_in_index;
 /* white-space error highlighting */
-#define WSEH_NEW (1<<12)
-#define WSEH_CONTEXT (1<<13)
-#define WSEH_OLD (1<<14)
+#define WSEH_NEW        (1<<12)
+#define WSEH_CONTEXT    (1<<13)
+#define WSEH_OLD        (1<<14)
 	unsigned ws_error_highlight;
 	const char *prefix;
 	int prefix_length;
diff --git a/ws.h b/ws.h
index 5ba676c559..23708efb73 100644
--- a/ws.h
+++ b/ws.h
@@ -7,19 +7,22 @@ struct strbuf;
 /*
  * whitespace rules.
  * used by both diff and apply
- * last two digits are tab width
+ * last two octal-digits are tab width (we support only up to 63).
  */
-#define WS_BLANK_AT_EOL         0100
-#define WS_SPACE_BEFORE_TAB     0200
-#define WS_INDENT_WITH_NON_TAB  0400
-#define WS_CR_AT_EOL           01000
-#define WS_BLANK_AT_EOF        02000
-#define WS_TAB_IN_INDENT       04000
-#define WS_TRAILING_SPACE      (WS_BLANK_AT_EOL|WS_BLANK_AT_EOF)
+#define WS_BLANK_AT_EOL         (1<<6)
+#define WS_SPACE_BEFORE_TAB     (1<<7)
+#define WS_INDENT_WITH_NON_TAB  (1<<8)
+#define WS_CR_AT_EOL            (1<<9)
+#define WS_BLANK_AT_EOF         (1<<10)
+#define WS_TAB_IN_INDENT        (1<<11)
+
+#define WS_TRAILING_SPACE       (WS_BLANK_AT_EOL|WS_BLANK_AT_EOF)
 #define WS_DEFAULT_RULE (WS_TRAILING_SPACE|WS_SPACE_BEFORE_TAB|8)
-#define WS_TAB_WIDTH_MASK        077
-/* All WS_* -- when extended, adapt diff.c emit_symbol */
-#define WS_RULE_MASK           07777
+#define WS_TAB_WIDTH_MASK       ((1<<6)-1)
+
+/* All WS_* -- when extended, adapt constants defined after diff.c:diff_symbol */
+#define WS_RULE_MASK            ((1<<12)-1)
+
 extern unsigned whitespace_rule_cfg;
 unsigned whitespace_rule(struct index_state *, const char *);
 unsigned parse_whitespace_rule(const char *);