diff --git a/score.py b/score.py
index 30f91df..a0157bb 100644
--- a/score.py
+++ b/score.py
@@ -5,15 +5,18 @@
     - ROC curve
     - PR curve
 """
-
+from glob import glob
 import argparse
 import json
 import os
 
 import pandas as pd
+import numpy as np
 from sklearn.metrics import roc_auc_score, average_precision_score
 
-from glob import glob
+GOLDSTANDARD_COLS = {"id": str, "disease": int}
+PREDICTION_COLS = {"id": str, "disease_probability": np.float64}
+
 
 def get_args():
     """Set up command-line interface and get arguments."""
@@ -37,7 +40,10 @@ def extract_gs_file(folder):
     """Extract gold standard file from folder."""
     files = glob(os.path.join(folder, "*"))
     if len(files) != 1:
-        raise ValueError(f"Expected exactly one gold standard file in folder. Got {len(files)}. Exiting.")
+        raise ValueError(
+            "Expected exactly one gold standard file in folder. "
+            f"Got {len(files)}. Exiting."
+        )
 
     return files[0]
 
@@ -52,8 +58,16 @@ def main():
     gold_file = extract_gs_file(args.goldstandard_folder)
 
     if res.get("validation_status") == "VALIDATED":
-        pred = pd.read_csv(args.predictions_file)
-        gold = pd.read_csv(gold_file)
+        pred = pd.read_csv(
+            args.predictions_file,
+            usecols=GOLDSTANDARD_COLS,
+            dtype=GOLDSTANDARD_COLS
+        )
+        gold = pd.read_csv(
+            gold_file,
+            usecols=PREDICTION_COLS,
+            dtype=PREDICTION_COLS
+        )
         scores = score(gold, "disease", pred, "disease_probability")
         status = "SCORED"
     else:
diff --git a/validate.py b/validate.py
index d5d32d4..c9373a2 100644
--- a/validate.py
+++ b/validate.py
@@ -5,7 +5,7 @@
     - `id` is a string
     - `disease_probability` is a float between 0 and 1
 """
-
+from glob import glob
 import argparse
 import json
 import os
@@ -13,23 +13,16 @@
 import numpy as np
 import pandas as pd
 
-from glob import glob
-
-EXPECTED_COLS = {
-    'id': str,
-    'disease_probability': np.float64
-}
+GOLDSTANDARD_COLS = {"id": str, "disease": int}
+EXPECTED_COLS = {"id": str, "disease_probability": np.float64}
 
 
 def get_args():
     """Set up command-line interface and get arguments."""
     parser = argparse.ArgumentParser()
-    parser.add_argument("-p", "--predictions_file",
-                        type=str, required=True)
-    parser.add_argument("-g", "--goldstandard_folder",
-                        type=str, required=True)
-    parser.add_argument("-o", "--output",
-                        type=str, default="results.json")
+    parser.add_argument("-p", "--predictions_file", type=str, required=True)
+    parser.add_argument("-g", "--goldstandard_folder", type=str, required=True)
+    parser.add_argument("-o", "--output", type=str, default="results.json")
     return parser.parse_args()
 
 
@@ -38,7 +31,7 @@ def check_dups(pred):
     duplicates = pred.duplicated(subset=["id"])
     if duplicates.any():
         return (
-            f"Found {duplicates.sum()} duplicate participant ID(s): "
+            f"Found {duplicates.sum()} duplicate ID(s): "
             f"{pred[duplicates].id.to_list()}"
         )
     return ""
@@ -50,7 +43,7 @@ def check_missing_ids(gold, pred):
     missing_ids = gold.index.difference(pred.index)
     if missing_ids.any():
         return (
-            f"Found {missing_ids.shape[0]} missing participant ID(s): "
+            f"Found {missing_ids.shape[0]} missing ID(s): "
             f"{missing_ids.to_list()}"
         )
     return ""
@@ -62,7 +55,7 @@ def check_unknown_ids(gold, pred):
     unknown_ids = pred.index.difference(gold.index)
     if unknown_ids.any():
         return (
-            f"Found {unknown_ids.shape[0]} unknown participant ID(s): "
+            f"Found {unknown_ids.shape[0]} unknown ID(s): "
             f"{unknown_ids.to_list()}"
         )
     return ""
@@ -72,34 +65,34 @@ def check_nan_values(pred):
     """Check for NAN predictions."""
     missing_probs = pred["disease_probability"].isna().sum()
     if missing_probs:
-        return (
-            f"'disease_probability' column contains {missing_probs} NaN value(s)."
-        )
+        return f"'disease_probability' column contains {missing_probs} NaN value(s)."
     return ""
 
 
 def check_prob_values(pred):
     """Check that probabilities are between [0, 1]."""
-    if (pred["disease_probability"] < 0).any() or (pred["disease_probability"] > 1).any():
-        return "'disease_probability' values should be between [0, 1] inclusive."
+    if (pred["disease_probability"] < 0).any() or \
+       (pred["disease_probability"] > 1).any():
+        return "'disease_probability' values should be between [0, 1]."
     return ""
 
 
 def extract_gs_file(folder):
-    """Extract gold standard file from folder."""
+    """Extract goldstandard file from folder."""
     files = glob(os.path.join(folder, "*"))
     if len(files) != 1:
-        raise ValueError(f"Expected exactly one gold standard file in folder. Got {len(files)}. Exiting.")
-
+        raise ValueError(
+            "Expected exactly one goldstandard file in folder. "
+            f"Got {len(files)}. Exiting."
+        )
     return files[0]
 
 
 def validate(gold_folder, pred_file):
     """Validate predictions file against goldstandard."""
     errors = []
-
     gold_file = extract_gs_file(gold_folder)
-    gold = pd.read_csv(gold_file, index_col="id")
+    gold = pd.read_csv(gold_file, dtype=GOLDSTANDARD_COLS, index_col="id")
     try:
         pred = pd.read_csv(
             pred_file,
@@ -140,10 +133,9 @@ def main():
     # truncate validation errors if >500 (character limit for sending email)
     if len(invalid_reasons) > 500:
         invalid_reasons = invalid_reasons[:496] + "..."
-    res = json.dumps({
-        "validation_status": status,
-        "validation_errors": invalid_reasons
-    })
+    res = json.dumps(
+        {"validation_status": status, "validation_errors": invalid_reasons}
+    )
 
     with open(args.output, "w") as out:
         out.write(res)