diff --git a/src/w_file.c b/src/w_file.c
index feb5772f..fd64d10e 100644
--- a/src/w_file.c
+++ b/src/w_file.c
@@ -46,7 +46,7 @@ static wad_file_class_t *wad_file_classes[] =
     &stdc_wad_file,
 };
 
-wad_file_t *W_OpenFile(char *path)
+wad_file_t *W_OpenFile(const char *path)
 {
     wad_file_t *result;
     int i;
diff --git a/src/w_file.h b/src/w_file.h
index 786b79bb..e31ceaf0 100644
--- a/src/w_file.h
+++ b/src/w_file.h
@@ -58,7 +58,7 @@ struct _wad_file_s
 // Open the specified file. Returns a pointer to a new wad_file_t 
 // handle for the WAD file, or NULL if it could not be opened.
 
-wad_file_t *W_OpenFile(char *path);
+wad_file_t *W_OpenFile(const char *path);
 
 // Close the specified WAD file.