diff --git a/exec.c b/exec.c
index 192b0cb..e5d6fff 100644
--- a/exec.c
+++ b/exec.c
@@ -42,7 +42,7 @@ exec(char *path, char **argv)
   // Arguments.
   arglen = 0;
   for(argc=0; argv[argc]; argc++)
-    arglen += strlen(argv[i]) + 1;
+    arglen += strlen(argv[argc]) + 1;
   arglen = (arglen+3) & ~3;
   sz += arglen + 4*(argc+1);