diff --git a/src/mbyte.c b/src/mbyte.c
index 411c3d9..c7de94e 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -4317,7 +4317,7 @@
     }
 
     /* copy "enc" to allocated memory, with room for two '-' */
-    r = alloc((unsigned)(STRLEN(enc) + 3));
+    r = alloc(STRLEN(enc) + 3);
     if (r != NULL)
     {
 	/* Make it all lower case and replace '_' with '-'. */
@@ -4603,7 +4603,7 @@
 	    /* Allocate enough room for most conversions.  When re-allocating
 	     * increase the buffer size. */
 	    len = len + fromlen * 2 + 40;
-	    p = alloc((unsigned)len);
+	    p = alloc(len);
 	    if (p != NULL && done > 0)
 		mch_memmove(p, result, done);
 	    vim_free(result);