diff --git a/src/crc32.c b/src/crc32.c
index cdad7bce..b19bec59 100644
--- a/src/crc32.c
+++ b/src/crc32.c
@@ -70,7 +70,7 @@ static const unsigned int crc_c[256] = {
 };
 
 
-uint32_t generate_crc32c(char *buffer, size_t length) {
+uint32_t generate_crc32c(const char *buffer, size_t length) {
   size_t i;
   uint32_t crc32 = ~0L;
 
diff --git a/src/crc32.h b/src/crc32.h
index c5b4245e..10e0e901 100644
--- a/src/crc32.h
+++ b/src/crc32.h
@@ -13,6 +13,6 @@
 # include <inttypes.h>
 #endif
 
-uint32_t generate_crc32c(char *string, size_t length);
+uint32_t generate_crc32c(const char *string, size_t length);
 
 #endif