diff --git a/library/base64.c b/library/base64.c
index 3f13fda..2b623b9 100644
--- a/library/base64.c
+++ b/library/base64.c
@@ -40,11 +40,11 @@
     /* For each range of values, if value is in that range, mask digit with
      * the corresponding value. Since value can only be in a single range,
      * only at most one masking will change digit. */
-    digit |= mbedtls_ct_uchar_mask_of_range(0, 25, value) & ('A' + value);
-    digit |= mbedtls_ct_uchar_mask_of_range(26, 51, value) & ('a' + value - 26);
-    digit |= mbedtls_ct_uchar_mask_of_range(52, 61, value) & ('0' + value - 52);
-    digit |= mbedtls_ct_uchar_mask_of_range(62, 62, value) & '+';
-    digit |= mbedtls_ct_uchar_mask_of_range(63, 63, value) & '/';
+    digit |= mbedtls_ct_uchar_in_range_if(0, 25, value, 'A' + value);
+    digit |= mbedtls_ct_uchar_in_range_if(26, 51, value, 'a' + value - 26);
+    digit |= mbedtls_ct_uchar_in_range_if(52, 61, value, '0' + value - 52);
+    digit |= mbedtls_ct_uchar_in_range_if(62, 62, value, '+');
+    digit |= mbedtls_ct_uchar_in_range_if(63, 63, value, '/');
     return digit;
 }
 
@@ -56,11 +56,11 @@
      * the corresponding value. Since c can only be in a single range,
      * only at most one masking will change val. Set val to one plus
      * the desired value so that it stays 0 if c is in none of the ranges. */
-    val |= mbedtls_ct_uchar_mask_of_range('A', 'Z', c) & (c - 'A' +  0 + 1);
-    val |= mbedtls_ct_uchar_mask_of_range('a', 'z', c) & (c - 'a' + 26 + 1);
-    val |= mbedtls_ct_uchar_mask_of_range('0', '9', c) & (c - '0' + 52 + 1);
-    val |= mbedtls_ct_uchar_mask_of_range('+', '+', c) & (c - '+' + 62 + 1);
-    val |= mbedtls_ct_uchar_mask_of_range('/', '/', c) & (c - '/' + 63 + 1);
+    val |= mbedtls_ct_uchar_in_range_if('A', 'Z', c, c - 'A' +  0 + 1);
+    val |= mbedtls_ct_uchar_in_range_if('a', 'z', c, c - 'a' + 26 + 1);
+    val |= mbedtls_ct_uchar_in_range_if('0', '9', c, c - '0' + 52 + 1);
+    val |= mbedtls_ct_uchar_in_range_if('+', '+', c, c - '+' + 62 + 1);
+    val |= mbedtls_ct_uchar_in_range_if('/', '/', c, c - '/' + 63 + 1);
     /* At this point, val is 0 if c is an invalid digit and v+1 if c is
      * a digit with the value v. */
     return val - 1;