diff -Nru nbd-3.8/nbdsrv.c nbd-3.8.new/nbdsrv.c
--- nbd-3.8/nbdsrv.c	2014-03-02 01:16:06.000000000 +0100
+++ nbd-3.8.new/nbdsrv.c	2014-08-30 15:13:25.760247069 +0200
@@ -21,11 +21,12 @@
 
 #include <cliserv.h>
 
-bool address_matches(const char* mask, const void* addr, int af, GError** err) {
+bool address_matches(const char* mask, const struct sockaddr* addr, GError** err) {
 	struct addrinfo *res, *aitmp, hints;
 	char *masksep;
 	char privmask[strlen(mask)+1];
 	int masklen;
+	int af = addr->sa_family;
 	int addrlen = af == AF_INET ? 4 : 16;
 
 	assert(af == AF_INET || af == AF_INET6);
@@ -50,7 +51,7 @@
 	}
 	aitmp = res;
 	while(res) {
-		const uint8_t* byte_s = addr;
+		const uint8_t* byte_s;
 		uint8_t* byte_t;
 		uint8_t mask = 0;
 		int len_left = masklen;
@@ -59,9 +60,11 @@
 		}
 		switch(af) {
 			case AF_INET:
+				byte_s = (const uint8_t*)(&(((struct sockaddr_in*)addr)->sin_addr));
 				byte_t = (uint8_t*)(&(((struct sockaddr_in*)(res->ai_addr))->sin_addr));
 				break;
 			case AF_INET6:
+				byte_s = (const uint8_t*)(&(((struct sockaddr_in6*)addr)->sin6_addr));
 				byte_t = (uint8_t*)(&(((struct sockaddr_in6*)(res->ai_addr))->sin6_addr));
 				break;
 		}
@@ -129,8 +132,7 @@
 		if(!(*pos)) {
 			continue;
 		}
-		struct sockaddr* sa = (struct sockaddr*)&opts->clientaddr;
-		if(address_matches(line, sa->sa_data, sa->sa_family, NULL)) {
+		if(address_matches(line, (struct sockaddr*)&opts->clientaddr, NULL)) {
 			fclose(f);
 			return 1;
 		}
diff -Nru nbd-3.8/nbdsrv.h nbd-3.8.new/nbdsrv.h
--- nbd-3.8/nbdsrv.h	2014-03-02 01:16:06.000000000 +0100
+++ nbd-3.8.new/nbdsrv.h	2014-08-30 15:07:39.724364463 +0200
@@ -124,13 +124,12 @@
   *
   * @param mask the address or netmask to check against, in ASCII representation
   * @param addr the address to check, in network byte order
-  * @param af the address family of the passed address (AF_INET or AF_INET6)
   *
   * @return true if the address matches the mask, false otherwise; in case of
   * failure to parse netmask, returns false with err set appropriately.
   * @todo decide what to do with v6-mapped IPv4 addresses.
   */
-bool address_matches(const char* mask, const void* addr, int af, GError** err);
+bool address_matches(const char* mask, const struct sockaddr* addr, GError** err);
 
 /**
   * Gets a byte to allow for address masking.