diff --git a/src/option.c b/src/option.c
index f8cb1ba..3f98f47 100644
--- a/src/option.c
+++ b/src/option.c
@@ -3287,8 +3287,8 @@
 	    if (opt_idx >= 0)
 	    {
 #if !defined(HAVE_AVAIL_MEM) && !defined(HAVE_TOTAL_MEM)
-		if ((long)options[opt_idx].def_val[VI_DEFAULT] > (long)n
-			|| (long)options[opt_idx].def_val[VI_DEFAULT] == 0L)
+		if ((long)(long_i)options[opt_idx].def_val[VI_DEFAULT] > (long)n
+		  || (long)(long_i)options[opt_idx].def_val[VI_DEFAULT] == 0L)
 #endif
 		    options[opt_idx].def_val[VI_DEFAULT] = (char_u *)n;
 	    }