RDMD can't eval code because of missing cstream module

[Meta via Digitalmars-d-learn]

I'm having trouble evaluating basic code with rdmd. It's 
complaining that std/cstream.d does not exist. I checked, and 
surely enough, it doesn't. My question is why is it looking for 
cstream.d? Is rdmd out of date, or is there a problem with my dmd 
install? I am on OSX 10.12.1 (Sierra) and installed dmd using 
Homebrew.

Here's the terminal output:

$ rdmd --eval="void main(){}"
/var/folders/q_/qpqhvkv57g36j1bq8qpm_mzw0000gn/T/.rdmd-501/eval.4090CC8525DF4BDD8D9084D5F66EDA46.d(6): Error: module cstream is in file 'std/cstream.d' which cannot be read

import path[0] = 
/var/folders/q_/qpqhvkv57g36j1bq8qpm_mzw0000gn/T/.rdmd-501
import path[1] = /usr/local/Cellar/dmd/2.072.0/include/dlang/dmd

Failed: ["dmd", "-d", "-v", "-c", 
"-of/var/folders/q_/qpqhvkv57g36j1bq8qpm_mzw0000gn/T/.rdmd-501/rdmd-eval.4090CC8525DF4BDD8D9084D5F66EDA46.d-35D613BB32BCB7BD6CC007543108437C/objs/eval.4090CC8525DF4BDD8D9084D5F66EDA46.o", "/var/folders/q_/qpqhvkv57g36j1bq8qpm_mzw0000gn/T/.rdmd-501/eval.4090CC8525DF4BDD8D9084D5F66EDA46.d", "-I/var/folders/q_/qpqhvkv57g36j1bq8qpm_mzw0000gn/T/.rdmd-501"]