diff --git a/src/dict.c b/src/dict.c
index 3824f40..9d94261 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -779,7 +779,7 @@
     for (p = *arg; ASCII_ISALNUM(*p) || *p == '_' || *p == '-'; ++p)
 	;
     tv->v_type = VAR_STRING;
-    tv->vval.v_string = vim_strnsave(*arg, (int)(p - *arg));
+    tv->vval.v_string = vim_strnsave(*arg, p - *arg);
 
     *arg = skipwhite(p);
     return OK;