diff --git a/tests/server/util.c b/tests/server/util.c
index 416195c061..627a626b78 100644
--- a/tests/server/util.c
+++ b/tests/server/util.c
@@ -54,6 +54,7 @@
 #include "getpart.h"
 #include "util.h"
 #include "timeval.h"
+#include "timediff.h"
 
 #ifdef USE_WINSOCK
 #undef  EINTR
@@ -64,6 +65,8 @@
 
 const char *serverlogfile = "log/server_default.log";
 
+static long timediff(struct timeval newer, struct timeval older);
+
 static struct timeval tvnow(void);
 
 /* This function returns a pointer to STATIC memory. It converts the given
@@ -457,7 +460,7 @@ static struct timeval tvnow(void)
 
 #endif
 
-long timediff(struct timeval newer, struct timeval older)
+static long timediff(struct timeval newer, struct timeval older)
 {
   timediff_t diff = newer.tv_sec-older.tv_sec;
   if(diff >= (LONG_MAX/1000))
diff --git a/tests/server/util.h b/tests/server/util.h
index 69121c587f..105e4f73c1 100644
--- a/tests/server/util.h
+++ b/tests/server/util.h
@@ -37,7 +37,6 @@ enum {
 
 char *data_to_hex(char *data, size_t len);
 void logmsg(const char *msg, ...) CURL_PRINTF(1, 2);
-long timediff(struct timeval newer, struct timeval older);
 
 #define SERVERLOGS_LOCKDIR "lock"  /* within logdir */