2 files changed, 10 insertions, 2 deletions
diff --git a/environ.c b/environ.c
index d884330e..29191ee5 100644
--- a/environ.c
+++ b/environ.c
@@ -208,9 +208,15 @@ environ_push(struct environ *env)
 
 /* Log the environment. */
 void
-environ_log(struct environ *env, const char *prefix)
+environ_log(struct environ *env, const char *fmt, ...)
 {
 	struct environ_entry	*envent;
+	va_list			 ap;
+	char			*prefix;
+
+	va_start(ap, fmt);
+	vasprintf(&prefix, fmt, ap);
+	va_end(ap);
 
 	RB_FOREACH(envent, environ, env) {
 		if (envent->value != NULL && *envent->name != '\0') {
@@ -218,6 +224,8 @@ environ_log(struct environ *env, const char *prefix)
 			    envent->value);
 		}
 	}
+
+	free(prefix);
 }
 
 /* Create initial environment for new child. */
diff --git a/tmux.h b/tmux.h
index 5fd57ee4..a91ed2e1 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1621,7 +1621,7 @@ void	environ_put(struct environ *, const char *);
 void	environ_unset(struct environ *, const char *);
 void	environ_update(struct options *, struct environ *, struct environ *);
 void	environ_push(struct environ *);
-void	environ_log(struct environ *, const char *);
+void printflike(2, 3) environ_log(struct environ *, const char *, ...);
 struct environ *environ_for_session(struct session *, int);
 
 /* tty.c */