diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 00000000000..5474734dcb3
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "md5sum/rust-crypto"]
+	path = md5sum/rust-crypto
+	url = git://github.com/DaGenix/rust-crypto.git
diff --git a/Makefile b/Makefile
index 0b998facf17..87177bbb82d 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,4 @@
-# Binaries
-RUSTC       ?= rustc
-RM          := rm
-
-# Flags
-RUSTCFLAGS  := --opt-level=3
-RMFLAGS     :=
+include common.mk
 
 # Possible programs
 PROGS       := \
@@ -16,6 +10,7 @@ PROGS       := \
   env \
   du \
   false \
+  md5sum \
   mkdir \
   paste \
   printenv \
@@ -70,8 +65,16 @@ command     = sh -c '$(1)'
 
 # Main exe build rule
 define EXE_BUILD
+ifeq ($(wildcard $(1)/Makefile),)
 build/$(1): $(1)/$(1).rs
 	$(call command,$(RUSTC) $(RUSTCFLAGS) -o build/$(1) $(1)/$(1).rs)
+clean_$(1):
+else
+build/$(1): $(1)/$(1).rs
+	cd $(1) && make
+clean_$(1):
+	cd $(1) && make clean
+endif
 endef
 
 # Test exe built rules
@@ -89,7 +92,7 @@ all: build $(EXES_PATHS)
 test: tmp $(addprefix test_,$(TESTS))
 	$(RM) -rf tmp
 
-clean:
+clean: $(addprefix clean_,$(EXES))
 	$(RM) -rf build tmp
 
 build:
diff --git a/README.md b/README.md
index 84e1b0f9319..3d98a6ebcaf 100644
--- a/README.md
+++ b/README.md
@@ -108,7 +108,6 @@ To do
 - ls-vdir
 - ls
 - make-prime-list
-- md5sum
 - mkfifo
 - mknod
 - mktemp
diff --git a/common.mk b/common.mk
new file mode 100644
index 00000000000..364ad755830
--- /dev/null
+++ b/common.mk
@@ -0,0 +1,7 @@
+# Binaries
+RUSTC       ?= rustc
+RM          := rm
+
+# Flags
+RUSTCFLAGS  := --opt-level=3
+RMFLAGS     :=
diff --git a/common/util.rs b/common/util.rs
index e26c715e582..db506e3bea5 100644
--- a/common/util.rs
+++ b/common/util.rs
@@ -18,6 +18,14 @@ macro_rules! show_error(
     })
 )
 
+#[macro_export]
+macro_rules! show_warning(
+    ($($args:expr),+) => ({
+        safe_write!(&mut ::std::io::stderr(), "{}: warning: ", ::NAME);
+        safe_writeln!(&mut ::std::io::stderr(), $($args),+);
+    })
+)
+
 #[macro_export]
 macro_rules! crash(
     ($exitcode:expr, $($args:expr),+) => ({
diff --git a/md5sum/Makefile b/md5sum/Makefile
new file mode 100644
index 00000000000..66f8479980c
--- /dev/null
+++ b/md5sum/Makefile
@@ -0,0 +1,15 @@
+include ../common.mk
+
+all: ../build/md5sum
+
+CRYPTO_DIR := rust-crypto
+CRYPTO_LIB := $(CRYPTO_DIR)/$(shell $(RUSTC) --crate-file-name --crate-type rlib $(CRYPTO_DIR)/src/rust-crypto/lib.rs)
+
+../build/md5sum: md5sum.rs $(CRYPTO_LIB)
+	$(RUSTC) $(RUSTFLAGS) -L $(CRYPTO_DIR) -o $@ $<
+
+$(CRYPTO_LIB): $(CRYPTO_DIR)/src/rust-crypto/*.rs
+	cd $(CRYPTO_DIR) && make
+
+clean:
+	cd $(CRYPTO_DIR) && make clean
diff --git a/md5sum/md5sum.rs b/md5sum/md5sum.rs
new file mode 100644
index 00000000000..00fc4dc0681
--- /dev/null
+++ b/md5sum/md5sum.rs
@@ -0,0 +1,158 @@
+#[crate_id(name = "md5sum", vers = "1.0.0", author = "Arcterus")];
+
+#[feature(macro_rules)];
+
+extern crate crypto = "rust-crypto";
+extern crate getopts;
+
+use std::io::fs::File;
+use std::io::BufferedReader;
+use std::os;
+use crypto::digest::Digest;
+
+#[path = "../common/util.rs"]
+mod util;
+
+static NAME: &'static str = "md5sum";
+static VERSION: &'static str = "1.0.0";
+
+fn main() {
+    let args = os::args();
+
+    let program = args[0].clone();
+
+    let opts = [
+        getopts::optflag("b", "binary", "read in binary mode"),
+        getopts::optflag("c", "check", "read MD5 sums from the FILEs and check them"),
+        getopts::optflag("", "tag", "create a BSD-style checksum"),
+        getopts::optflag("t", "text", "read in text mode (default)"),
+        getopts::optflag("q", "quiet", "don't print OK for each successfully verified file"),
+        getopts::optflag("s", "status", "don't output anything, status code shows success"),
+        getopts::optflag("", "strict", "exit non-zero for improperly formatted checksum lines"),
+        getopts::optflag("w", "warn", "warn about improperly formatted checksum lines"),
+        getopts::optflag("h", "help", "display this help and exit"),
+        getopts::optflag("V", "version", "output version information and exit")
+    ];
+
+    let matches = match getopts::getopts(args.tail(), opts) {
+        Ok(m) => m,
+        Err(f) => crash!(1, "{}", f.to_err_msg())
+    };
+
+    if matches.opt_present("help") {
+        println!("{} v{}", NAME, VERSION);
+        println!("");
+        println!("Usage:");
+        println!("  {} [OPTION]... [FILE]...", program);
+        println!("");
+        print!("{}", getopts::usage("Compute and check MD5 message digests.", opts));
+    } else if matches.opt_present("version") {
+        println!("{} v{}", NAME, VERSION);
+    } else {
+        let binary = matches.opt_present("binary");
+        let check = matches.opt_present("check");
+        let tag = matches.opt_present("tag");
+        let status = matches.opt_present("status");
+        let quiet = matches.opt_present("quiet") || status;
+        let strict = matches.opt_present("strict");
+        let warn = matches.opt_present("warn") && !status;
+        md5sum(matches.free, binary, check, tag, status, quiet, strict, warn);
+    }
+}
+
+fn md5sum(files: Vec<~str>, binary: bool, check: bool, tag: bool, status: bool, quiet: bool, strict: bool, warn: bool) {
+    let mut md5 = crypto::md5::Md5::new();
+    let bytes = md5.output_bits() / 4;
+    let mut bad_format = 0;
+    let mut failed = 0;
+    for filename in files.iter() {
+        let filename: &str = *filename;
+        let mut file = safe_unwrap!(File::open(&Path::new(filename)));
+        if check {
+            let mut buffer = BufferedReader::new(file);
+            for (i, line) in buffer.lines().enumerate() {
+                let line = safe_unwrap!(line);
+                let (ck_filename, sum) = match from_gnu(line, bytes) {
+                    Some(m) => m,
+                    None => match from_bsd(line, bytes) {
+                        Some(m) => m,
+                        None => {
+                            bad_format += 1;
+                            if strict {
+                                os::set_exit_status(1);
+                            }
+                            if warn {
+                                show_warning!("{}: {}: improperly formatted MD5 checksum line", filename, i + 1);
+                            }
+                            continue;
+                        }
+                    }
+                };
+                let real_sum = calc_sum(&mut md5, &mut safe_unwrap!(File::open(&Path::new(ck_filename))), binary);
+                if sum == real_sum {
+                    if !quiet {
+                        println!("{}: OK", ck_filename);
+                    }
+                } else {
+                    if !status {
+                        println!("{}: FAILED", ck_filename);
+                    }
+                    failed += 1;
+                    os::set_exit_status(1);
+                }
+            }
+        } else {
+            let sum = calc_sum(&mut md5, &mut file, binary);
+            if tag {
+                println!("MD5 ({}) = {}", filename, sum);
+            } else {
+                println!("{}  {}", sum, filename);
+            }
+        }
+    }
+    if !status {
+        if bad_format == 1 {
+            show_warning!("{} line is improperly formatted", bad_format);
+        } else if bad_format > 1 {
+            show_warning!("{} lines are improperly formatted", bad_format);
+        }
+        if failed > 0 {
+            show_warning!("{} computed checksum did NOT match", failed);
+        }
+    }
+}
+
+fn calc_sum(md5: &mut crypto::md5::Md5, file: &mut File, binary: bool) -> ~str {
+    let data =
+        if binary {
+            safe_unwrap!(file.read_to_end())
+        } else {
+            let val = safe_unwrap!(file.read_to_str()).into_bytes();  // XXX: i don't know why the variable is necessary
+            val
+        };
+    md5.reset();
+    md5.input(data);
+    md5.result_str()
+}
+
+fn from_gnu<'a>(line: &'a str, bytes: uint) -> Option<(&'a str, &'a str)> {
+    let sum = line.slice_to(bytes);
+    if sum.len() < bytes || line.slice(bytes, bytes + 2) != "  " {
+        None
+    } else {
+        Some((line.slice(bytes + 2, line.len() - 1), sum))
+    }
+}
+
+fn from_bsd<'a>(line: &'a str, bytes: uint) -> Option<(&'a str, &'a str)> {
+    if line.slice(0, 5) == "MD5 (" {
+        let rparen = match line.find(')') {
+            Some(m) => m,
+            None => return None
+        };
+        if rparen > 5 && line.slice(rparen + 1, rparen + 4) == " = " && line.len() - 1 == rparen + 4 + bytes {
+            return Some((line.slice(5, rparen), line.slice(rparen + 4, line.len() - 1)));
+        }
+    }
+    None
+}
\ No newline at end of file
diff --git a/md5sum/rust-crypto b/md5sum/rust-crypto
new file mode 160000
index 00000000000..fd168c53c00
--- /dev/null
+++ b/md5sum/rust-crypto
@@ -0,0 +1 @@
+Subproject commit fd168c53c00475c4fae3efc329301e80451bd967
diff --git a/truncate/truncate.rs b/truncate/truncate.rs
index 566611f5de6..17882e5fe2b 100644
--- a/truncate/truncate.rs
+++ b/truncate/truncate.rs
@@ -176,7 +176,7 @@ fn parse_size(size: ~str) -> (u64, TruncateMode) {
             }
         }
         slice
-    }.bytes().to_owned_vec();
+    }.to_owned().into_bytes();
     let mut number = match u64::parse_bytes(bytes, 10) {
         Some(num) => num,
         None => {