diff --git a/libc/misc/lib_crc16.c b/libc/misc/lib_crc16.c
index 76e8dac8a5..0240e41ab2 100644
--- a/libc/misc/lib_crc16.c
+++ b/libc/misc/lib_crc16.c
@@ -114,9 +114,9 @@ uint16_t crc16part(FAR const uint8_t *src, size_t len, uint16_t crc16val)
 {
   size_t i;
 
-  for (i = 0;  i < len;  i++)
+  for (i = 0; i < len; i++)
     {
-      crc16val = crc16_tab[((crc16val >> 8) & 255)] ^ (crc16val << 8) ^ src[i];
+      crc16val = crc16_tab[((crc16val >> 8) & 0xff) ^ src[i]] ^ (crc16val << 8);
     }
 
   return crc16val;
diff --git a/libc/misc/lib_crc32.c b/libc/misc/lib_crc32.c
index 40e7c014a0..cd6ac0758a 100644
--- a/libc/misc/lib_crc32.c
+++ b/libc/misc/lib_crc32.c
@@ -102,9 +102,9 @@ uint32_t crc32part(FAR const uint8_t *src, size_t len, uint32_t crc32val)
 {
   size_t i;
 
-  for (i = 0;  i < len;  i++)
+  for (i = 0; i < len; i++)
     {
-      crc32val = crc32_tab[(crc32val ^ src[i]) & 0xff] ^ (crc32val >> 8);
+      crc32val = crc32_tab[(crc32val & 0xff) ^ src[i]] ^ (crc32val >> 8);
     }
   return crc32val;
 }
diff --git a/libc/misc/lib_crc8.c b/libc/misc/lib_crc8.c
index ae3e01d5d7..4da049c60a 100644
--- a/libc/misc/lib_crc8.c
+++ b/libc/misc/lib_crc8.c
@@ -124,13 +124,13 @@ uint8_t crc8part(FAR const uint8_t *src, size_t len, uint8_t crc8val)
 {
   size_t i;
 
-  crc8val ^= 0xFF;
-  for (i = 0;  i < len;  i++)
+  crc8val ^= 0xff;
+  for (i = 0; i < len; i++)
     {
       crc8val = crc8_tab[crc8val ^ src[i]];
     }
 
-  return crc8val ^ 0xFF;
+  return crc8val ^ 0xff;
 }
 
 /************************************************************************************************