diff --git a/Cargo.toml b/Cargo.toml
index d73a932..372d1d7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,10 +47,11 @@ subtle = { version = "^2.2.1", default-features = false }
 serde = { version = "1.0", default-features = false, optional = true, features = ["derive"] }
 packed_simd = { version = "0.3", features = ["into_bits"], optional = true }
 zeroize = { version = "1", default-features = false }
+engine25519-as = { path="../engine25519-as" }
 
 [features]
 nightly = ["subtle/nightly"]
-default = ["std", "u64_backend"]
+default = ["std", "u32_backend"]
 std = ["alloc", "subtle/std", "rand_core/std"]
 alloc = ["zeroize/alloc"]
 
diff --git a/src/field.rs b/src/field.rs
index 54d048d..e14653f 100644
--- a/src/field.rs
+++ b/src/field.rs
@@ -457,4 +457,70 @@ mod test {
     fn batch_invert_empty() {
         FieldElement::batch_invert(&mut []);
     }
+
+    #[test]
+    fn make_vectors() {
+        use std::fs::File;
+        use std::io::prelude::*;
+        use std::path::Path;
+        use engine25519_as::*;
+
+        fn write_helper(file: &mut File, elem: FieldElement) {
+            let elem_bytes = elem.to_bytes();
+            let _ = file.write(&elem_bytes);
+            /*
+            for i in 0..elem_bytes.len()/4 {
+                let word: u32 = elem_bytes.pread::<u32>(i).unwrap();
+                let _ = write!(file, "{:02x}", elem_bytes[i]);
+            }
+            let _ = write!(file, " ");*/
+        }
+
+        let a = FieldElement::one();
+        let b = FieldElement::minus_one();
+        let q = &a + &b;
+
+        let mcode = assemble_engine25519!(
+            start:
+                add %0, %1, %2
+        );
+
+        let path = Path::new("test_vectors.bin");
+        let mut file = File::create(&path).unwrap();
+
+        // insert machine code
+        // Metadata record:
+        //   0x0 [31   load address   16]                                 [15  length of code  0]
+        //   0x4 [31  N registers to load  27] [26 W window 23] [22  X number of vectors sets  0]
+        //   0x8 [microcode] (variable length)
+        //   [ padding of 0x0 until 0x20 * align ]
+        //   0x20*align [X test vectors]
+        // Convention:
+        //   Check result is always in r31
+        //   N Registers loaded starting at r0 into window W
+        let mcode_len = mcode.len();
+        let _ = file.write(&( ((0x0 & 0xFFFF << 16)
+                             | (mcode_len & 0xFFFF)
+                             ) as u32)
+                            .to_le_bytes() ); // load address 0 + code length
+        let _ = file.write(&( ((2 & 0x1F) << 27
+                             | (0 & 0xF) << 23
+                             | (1 & 0x3F_FFFF)
+                             ) as u32)
+                            .to_le_bytes() ); // 2 registers, window 0, 1 vector
+        // the actual microcode
+        for i in 0..mcode_len {
+            let _ = file.write(&(mcode[i] as u32).to_le_bytes());
+        }
+
+        // pad with 0's to a 256-bit stride
+        for _ in 0..(8 - ((2 + mcode_len) % 8)) {  // 2 words for metadata + code length
+            let _ = file.write(&[0,0,0,0]); // write out 32-bit words of 0 (as array of u8)
+        }
+
+        // test vectors
+        write_helper(&mut file, a);
+        write_helper(&mut file, b);
+        write_helper(&mut file, q);
+    }
 }
diff --git a/src/lib.rs b/src/lib.rs
index e1409a2..20cf769 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -59,6 +59,9 @@ extern crate serde;
 #[macro_use]
 pub(crate) mod macros;
 
+#[macro_use]
+extern crate engine25519_as;
+
 //------------------------------------------------------------------------
 // curve25519-dalek public modules
 //------------------------------------------------------------------------