diff --git a/specs/ml/file_io_contract.t27 b/specs/ml/file_io_contract.t27
index 07969972ec..6ea9b36c56 100644
--- a/specs/ml/file_io_contract.t27
+++ b/specs/ml/file_io_contract.t27
@@ -235,7 +235,7 @@ pub fn get_u32(buf: []const u8, off: i32) -> u32 {
     return x;
 }
 
-fn byte_sum(buf: []const u8, n: i32) -> u32 {
+pub fn byte_sum(buf: []const u8, n: i32) -> u32 {
     var s : u32 = 0;
     var i : i32 = 0;
     while (i < n) {
diff --git a/specs/ml/train_slice_model.t27 b/specs/ml/train_slice_model.t27
index 332cce6ded..3698852929 100644
--- a/specs/ml/train_slice_model.t27
+++ b/specs/ml/train_slice_model.t27
@@ -95,17 +95,6 @@ fn get_f32(buf: []const u8, off: i32) -> f64 {
     return @floatCast(f);
 }
 
-fn byte_total(buf: []const u8, n: i32) -> u32 {
-    var s : u32 = 0;
-    var i : i32 = 0;
-    while (i < n) {
-        const b : u32 = @intCast(buf[@intCast(i)]);
-        s = s + b;
-        i = i + 1;
-    }
-    return s;
-}
-
 /// Train the slice for `steps` steps of learning rate `lr` from its fixed initial state.
 /// losses[0] is the mean loss before any step, losses[1] the mean loss after the last one.
 pub fn train(steps: u32, lr: f64, losses: []f64) -> void {
@@ -148,7 +137,7 @@ pub fn pack(buf: []u8, steps: u32, losses: []const f64) -> void {
         buf[@intCast(OFF_TRITS + k)] = code;
         k = k + 1;
     }
-    put_u32(buf, OFF_SUM, byte_total(buf, OFF_SUM));
+    put_u32(buf, OFF_SUM, byte_sum(buf, OFF_SUM));
 }
 
 /// Accept a checkpoint image only if its magic, its checksum and the losses it carries are right:
@@ -157,7 +146,7 @@ pub fn check_image(buf: []const u8) -> i32 {
     if (buf[0] != MAGIC0 or buf[1] != MAGIC1 or buf[2] != MAGIC2 or buf[3] != MAGIC3) {
         return TRAIN_ERR_MAGIC;
     }
-    if (get_u32(buf, OFF_SUM) != byte_total(buf, OFF_SUM)) {
+    if (get_u32(buf, OFF_SUM) != byte_sum(buf, OFF_SUM)) {
         return TRAIN_ERR_SUM;
     }
     const first : f64 = get_f32(buf, OFF_FIRST);