PVS-Studio warning V529 for ReactOS

int BlockEnvToEnvironA(void)
{
  ....
  for (envptr--; envptr >= _environ; envptr--);
    free(*envptr);
  ....
}

This suspicious code was found in ReactOS project by PVS-Studio static code analyzer.
Warning message is:
V529 Odd semicolon ';' after 'for' operator. environ.c 67

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