diff --git a/include/coap/address.h b/include/coap/address.h
index f08b4852..1c21cdcd 100644
--- a/include/coap/address.h
+++ b/include/coap/address.h
@@ -1,6 +1,6 @@
 /* address.h -- representation of network addresses
  *
- * Copyright (C) 2010,2011 Olaf Bergmann <bergmann@tzi.org>
+ * Copyright (C) 2010,2011,2015 Olaf Bergmann <bergmann@tzi.org>
  *
  * This file is part of the CoAP library libcoap. Please see
  * README for terms of use. 
@@ -88,28 +88,12 @@ typedef struct coap_address_t {
   } addr;
 } coap_address_t;
 
-static inline int 
-_coap_address_equals_impl(const coap_address_t *a,
-			  const coap_address_t *b) {
-  if (a->size != b->size || a->addr.sa.sa_family != b->addr.sa.sa_family)
-    return 0;
-  
-  /* need to compare only relevant parts of sockaddr_in6 */
- switch (a->addr.sa.sa_family) {
- case AF_INET:
-   return 
-     a->addr.sin.sin_port == b->addr.sin.sin_port && 
-     memcmp(&a->addr.sin.sin_addr, &b->addr.sin.sin_addr, 
-	    sizeof(struct in_addr)) == 0;
- case AF_INET6:
-   return a->addr.sin6.sin6_port == b->addr.sin6.sin6_port && 
-     memcmp(&a->addr.sin6.sin6_addr, &b->addr.sin6.sin6_addr, 
-	    sizeof(struct in6_addr)) == 0;
- default: /* fall through and signal error */
-   ;
- }
- return 0;
-}
+/**
+ * Compares given address objects @p a and @p b. This function returns
+ * @c 1 if addresses are equal, @c 0 otherwise. The parameters @p a
+ * and @p b must not be @c NULL;
+ */
+int coap_address_equals(const coap_address_t *a, const coap_address_t *b);
 
 static inline int
 _coap_address_isany_impl(const coap_address_t *a) {
@@ -160,6 +144,7 @@ coap_address_init(coap_address_t *addr) {
 #endif
 }
 
+#ifndef WITH_POSIX
 /**
  * Compares given address objects @p a and @p b. This function returns
  * @c 1 if addresses are equal, @c 0 otherwise. The parameters @p a
@@ -170,6 +155,7 @@ coap_address_equals(const coap_address_t *a, const coap_address_t *b) {
   assert(a); assert(b);
   return _coap_address_equals_impl(a, b);
 }
+#endif
 
 /**
  * Checks if given address object @p a denotes the wildcard
diff --git a/src/address.c b/src/address.c
new file mode 100644
index 00000000..e237881a
--- /dev/null
+++ b/src/address.c
@@ -0,0 +1,48 @@
+/* address.c -- representation of network addresses
+ *
+ * Copyright (C) 2015 Olaf Bergmann <bergmann@tzi.org>
+ *
+ * This file is part of the CoAP library libcoap. Please see
+ * README for terms of use.
+ */
+
+#ifdef WITH_POSIX
+#include <assert.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include "address.h"
+
+int 
+coap_address_equals(const coap_address_t *a, const coap_address_t *b) {
+  assert(a); assert(b);
+
+  if (a->size != b->size || a->addr.sa.sa_family != b->addr.sa.sa_family)
+    return 0;
+  
+  /* need to compare only relevant parts of sockaddr_in6 */
+ switch (a->addr.sa.sa_family) {
+ case AF_INET:
+   return 
+     a->addr.sin.sin_port == b->addr.sin.sin_port && 
+     memcmp(&a->addr.sin.sin_addr, &b->addr.sin.sin_addr, 
+	    sizeof(struct in_addr)) == 0;
+ case AF_INET6:
+   return a->addr.sin6.sin6_port == b->addr.sin6.sin6_port && 
+     memcmp(&a->addr.sin6.sin6_addr, &b->addr.sin6.sin6_addr, 
+	    sizeof(struct in6_addr)) == 0;
+ default: /* fall through and signal error */
+   ;
+ }
+ return 0;
+}
+
+#else /* WITH_POSIX */
+
+/* make compilers happy that do not like empty modules */
+static inline void dummy()
+{
+}
+
+#endif /* not WITH_POSIX */
+