diff --git a/include/libbb.h b/include/libbb.h
index f22e58e27..2059567e0 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1248,7 +1248,7 @@ extern void run_shell(const char *shell, int loginshell, const char *command, co
  * Note that getpwuid result might need xstrdup'ing
  * if there is a possibility of intervening getpwxxx() calls.
  */
-const char *get_shell_name(void);
+const char *get_shell_name(void) FAST_FUNC;
 
 #if ENABLE_SELINUX
 extern void renew_current_security_context(void) FAST_FUNC;
diff --git a/libbb/get_shell_name.c b/libbb/get_shell_name.c
index c930afd94..5aebe9cdc 100644
--- a/libbb/get_shell_name.c
+++ b/libbb/get_shell_name.c
@@ -8,7 +8,7 @@
 
 #include "libbb.h"
 
-const char *get_shell_name(void)
+const char* FAST_FUNC get_shell_name(void)
 {
 	struct passwd *pw;
 	char *shell;