diff --git a/lib/memdebug.c b/lib/memdebug.c
index ea3eb8559..99bce6a5d 100644
--- a/lib/memdebug.c
+++ b/lib/memdebug.c
@@ -264,7 +264,7 @@ int curl_accept(int s, void *saddr, void *saddrlen,
 }
 
 /* separate function to allow libcurl to mark a "faked" close */
-int curl_mark_sclose(int sockfd, int line, const char *source)
+void curl_mark_sclose(int sockfd, int line, const char *source)
 {
   if(logfile)
     fprintf(logfile, "FD %s:%d sclose(%d)\n",
diff --git a/lib/memdebug.h b/lib/memdebug.h
index 57e89b1d4..ed1177b59 100644
--- a/lib/memdebug.h
+++ b/lib/memdebug.h
@@ -57,7 +57,7 @@ CURL_EXTERN void curl_memlimit(long limit);
 
 /* file descriptor manipulators */
 CURL_EXTERN int curl_socket(int domain, int type, int protocol, int line , const char *);
-CURL_EXTERN int curl_mark_sclose(int sockfd, int, const char *source);
+CURL_EXTERN void curl_mark_sclose(int sockfd, int, const char *source);
 CURL_EXTERN int curl_sclose(int sockfd, int, const char *source);
 CURL_EXTERN int curl_accept(int s, void *addr, void *addrlen,
                             int line, const char *source);