diff --git a/crc/sha512.c b/crc/sha512.c
index 0d44ace..9268a49 100644
--- a/crc/sha512.c
+++ b/crc/sha512.c
@@ -162,10 +162,10 @@
 void sha512_update(struct sha512_ctx *sctx, const uint8_t *data,
 		   unsigned int len)
 {
-	unsigned int i, index, part_len;
+	unsigned int i, idx, part_len;
 
 	/* Compute number of bytes mod 128 */
-	index = (unsigned int)((sctx->count[0] >> 3) & 0x7F);
+	idx = (unsigned int)((sctx->count[0] >> 3) & 0x7F);
 	
 	/* Update number of bits */
 	if ((sctx->count[0] += (len << 3)) < (len << 3)) {
@@ -175,23 +175,23 @@
 		sctx->count[1] += (len >> 29);
 	}
 	
-        part_len = 128 - index;
+        part_len = 128 - idx;
 	
 	/* Transform as many times as possible. */
 	if (len >= part_len) {
-		memcpy(&sctx->buf[index], data, part_len);
+		memcpy(&sctx->buf[idx], data, part_len);
 		sha512_transform(sctx->state, sctx->W, sctx->buf);
 
 		for (i = part_len; i + 127 < len; i+=128)
 			sha512_transform(sctx->state, sctx->W, &data[i]);
 
-		index = 0;
+		idx = 0;
 	} else {
 		i = 0;
 	}
 
 	/* Buffer remaining input */
-	memcpy(&sctx->buf[index], &data[i], len - i);
+	memcpy(&sctx->buf[idx], &data[i], len - i);
 
 	/* erase our data */
 	memset(sctx->W, 0, sizeof(sctx->W));