diff --git a/lib/crc32.c b/lib/crc32.c
index eae6582..3064c65 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -90,6 +90,10 @@ static const uint32_t crc32_table[256] =
   0x2d02ef8d
 };
 
+/* crc32 is owned by zlib. */
+#ifndef crc32
+#define crc32 eu_crc32
+#endif
 uint32_t
 crc32 (uint32_t crc, unsigned char *buf, size_t len)
 {
diff --git a/lib/libeu.h b/lib/libeu.h
index e849a79..522fc74 100644
--- a/lib/libeu.h
+++ b/lib/libeu.h
@@ -42,6 +42,8 @@ extern char *xstrndup (const char *, size_t) __attribute__ ((__malloc__));
 extern char *xasprintf(const char *fmt, ...)
 	__attribute__ ((format (printf, 1, 2))) __attribute__ ((__malloc__));
 
+/* crc32 is owned by zlib. */
+#define crc32 eu_crc32
 extern uint32_t crc32 (uint32_t crc, unsigned char *buf, size_t len);
 extern int crc32_file (int fd, uint32_t *resp);