diff --git a/nbase/nbase_memalloc.c b/nbase/nbase_memalloc.c
index 5a9d2166e..33b1cd647 100644
--- a/nbase/nbase_memalloc.c
+++ b/nbase/nbase_memalloc.c
@@ -98,7 +98,9 @@
 #include "nbase.h"
 #include <stdio.h>
 
-static void fatal(char *fmt, ...) __attribute__ ((format(printf, 1, 2)));
+static void fatal(char *fmt, ...)
+  __attribute__ ((noreturn))
+  __attribute__ ((format (printf, 1, 2)));
 
 static void fatal(char *fmt, ...) {
   va_list ap;
diff --git a/nsock/src/error.h b/nsock/src/error.h
index 710ce4335..c7f17b2a5 100644
--- a/nsock/src/error.h
+++ b/nsock/src/error.h
@@ -75,9 +75,13 @@
 #include <unistd.h>
 #endif
 
-void fatal(char *fmt, ...) __attribute__((noreturn));
+void fatal(char *fmt, ...)
+  __attribute__ ((noreturn))
+  __attribute__ ((format (printf, 1, 2)));
 
-void pfatal(char *fmt, ...) __attribute__((noreturn));
+void pfatal(char *fmt, ...)
+  __attribute__ ((noreturn))
+  __attribute__ ((format (printf, 1, 2)));
 
 void gh_perror(char *err, ...);