diff --git a/ext/standard/crc32.c b/ext/standard/crc32.c
index 92dce07db54ea..221b864ba58d5 100644
--- a/ext/standard/crc32.c
+++ b/ext/standard/crc32.c
@@ -63,7 +63,7 @@ static inline int has_crc32_insn() {
 #  pragma GCC push_options
 #  pragma GCC target ("+nothing+crc")
 # endif
-static uint32_t crc32_aarch64(uint32_t crc, char *p, size_t nr) {
+static uint32_t crc32_aarch64(uint32_t crc, const char *p, size_t nr) {
 	while (nr >= sizeof(uint64_t)) {
 		crc = __crc32d(crc, *(uint64_t *)p);
 		p += sizeof(uint64_t);