diff --git a/src/mbyte.c b/src/mbyte.c
index 697e585..6df3a15 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -2850,7 +2850,7 @@
     };
 
     int bot = 0;
-    int top = sizeof(classes) / sizeof(struct clinterval) - 1;
+    int top = ARRAY_LENGTH(classes) - 1;
     int mid;
 
     // First quick check for Latin1 characters, use 'iskeyword'.
@@ -3948,7 +3948,7 @@
     };
 
     int first = 0;
-    int last  = sizeof(BOL_prohibition_punct)/sizeof(int) - 1;
+    int last  = ARRAY_LENGTH(BOL_prohibition_punct) - 1;
     int mid   = 0;
 
     while (first < last)
@@ -3998,7 +3998,7 @@
     };
 
     int first = 0;
-    int last  = sizeof(EOL_prohibition_punct)/sizeof(int) - 1;
+    int last  = ARRAY_LENGTH(EOL_prohibition_punct) - 1;
     int mid   = 0;
 
     while (first < last)