diff --git a/src/sbbs3/load_cfg.c b/src/sbbs3/load_cfg.c
index c2354b4122bf09c32a1b82e923e0b8e3a613453f..e45a82061bfacf29537b818736a0fe264d281927 100644
--- a/src/sbbs3/load_cfg.c
+++ b/src/sbbs3/load_cfg.c
@@ -357,7 +357,7 @@ static void free_attr_cfg(scfg_t* cfg)
 	cfg->total_colors=0;
 }
 
-char* DLLCALL prep_dir(char* base, char* path, size_t buflen)
+char* DLLCALL prep_dir(const char* base, char* path, size_t buflen)
 {
 #ifdef __unix__
 	char	*p;
diff --git a/src/sbbs3/sbbs.h b/src/sbbs3/sbbs.h
index 15093f39c02d40c234ea808d81d0f0b74be2807b..3953a482df40ab0f8b92164164da93ac5e7bcace 100644
--- a/src/sbbs3/sbbs.h
+++ b/src/sbbs3/sbbs.h
@@ -953,7 +953,7 @@ extern "C" {
 
 
 	/* scfglib1.c */
-	DLLEXPORT char *	DLLCALL prep_dir(char* base, char* dir, size_t buflen);
+	DLLEXPORT char *	DLLCALL prep_dir(const char* base, char* dir, size_t buflen);
 
 	/* logfile.cpp */
 	DLLEXPORT int		DLLCALL errorlog(scfg_t* cfg, const char* host, const char* text);