diff --git a/socket.c b/socket.c
index a3722953..70d8ffd8 100644
--- a/socket.c
+++ b/socket.c
@@ -41,6 +41,13 @@
 
 #include "memdbg.h"
 
+const int proto_overhead[] = { /* indexed by PROTO_x */
+  IPv4_UDP_HEADER_SIZE,
+  IPv4_TCP_HEADER_SIZE,
+  IPv4_TCP_HEADER_SIZE,
+  IPv4_TCP_HEADER_SIZE
+};
+
 /*
  * Functions related to the translation of DNS names to IP addresses.
  */
diff --git a/socket.h b/socket.h
index f0d9a437..28bf41f8 100644
--- a/socket.h
+++ b/socket.h
@@ -454,11 +454,7 @@ int proto_remote (int proto, bool remote);
 #define IPv4_TCP_HEADER_SIZE              40
 #define IPv6_UDP_HEADER_SIZE              40
 
-static const int proto_overhead[] = { /* indexed by PROTO_x */
-  IPv4_UDP_HEADER_SIZE,
-  IPv4_TCP_HEADER_SIZE,
-  IPv4_TCP_HEADER_SIZE
-};
+extern const int proto_overhead[];
 
 static inline int
 datagram_overhead (int proto)