diff --git a/src/map.c b/src/map.c
index 9a6cdb1..92f7651 100644
--- a/src/map.c
+++ b/src/map.c
@@ -3034,8 +3034,8 @@
  * Called when langmap option is set; the language map can be
  * changed at any time!
  */
-    void
-langmap_set(void)
+    char *
+did_set_langmap(optset_T *args UNUSED)
 {
     char_u  *p;
     char_u  *p2;
@@ -3088,9 +3088,11 @@
 	    }
 	    if (to == NUL)
 	    {
+		// TODO: Need to use errbuf argument for this error message
+		// and return it.
 		semsg(_(e_langmap_matching_character_missing_for_str),
 							     transchar(from));
-		return;
+		return NULL;
 	    }
 
 	    if (from >= 256)
@@ -3110,8 +3112,10 @@
 		    {
 			if (p[0] != ',')
 			{
+			    // TODO: Need to use errbuf argument for this error
+			    // message and return it.
 			    semsg(_(e_langmap_extra_characters_after_semicolon_str), p);
-			    return;
+			    return NULL;
 			}
 			++p;
 		    }
@@ -3120,6 +3124,8 @@
 	    }
 	}
     }
+
+    return NULL;
 }
 #endif