diff --git a/test/problems/skel/generators/generators.yaml b/test/problems/skel/generators/generators.yaml
index 8072671a..968d5d73 100644
--- a/test/problems/skel/generators/generators.yaml
+++ b/test/problems/skel/generators/generators.yaml
@@ -1,4 +1,4 @@
-solution: /submissions/accepted/hello.cpp
+solution: /submissions/accepted/hello.py
 #visualizer: /visualizers/asy.sh
 # By default, generated files are not ignored.
 #gitignore_generated: false
diff --git a/test/problems/skel/input_validators/input_validator.cpp b/test/problems/skel/input_validators/input_validator.cpp
deleted file mode 100644
index 2ebceb44..00000000
--- a/test/problems/skel/input_validators/input_validator.cpp
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <iostream>
-
-int main(int argc, char *argv[]) {
-    int n;
-    std::cin >> n;
-    return 0 <= n && n < 1000000 ? 42 : 43;
-}
diff --git a/test/problems/skel/input_validators/input_validator.py b/test/problems/skel/input_validators/input_validator.py
new file mode 100644
index 00000000..bf52c8c4
--- /dev/null
+++ b/test/problems/skel/input_validators/input_validator.py
@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+
+try:
+    if 0 <= int(input()) < 1_000_000:
+        exit(42)
+    else:
+        print("Out of range")
+        exit(43)
+except Exception as e:
+    print(e)
+    exit(43)
diff --git a/test/problems/skel/output_validators/output_validator.cpp b/test/problems/skel/output_validators/output_validator.cpp
deleted file mode 100644
index 55af96d4..00000000
--- a/test/problems/skel/output_validators/output_validator.cpp
+++ /dev/null
@@ -1,9 +0,0 @@
-#include <iostream>
-#include <fstream>
-
-int main(int argc, char *argv[]) {
-    std::ifstream team_ans(argv[2]);
-
-    double answer;
-    return (team_ans >> answer) ? 42 : 43;
-}
diff --git a/test/problems/skel/output_validators/output_validator.py b/test/problems/skel/output_validators/output_validator.py
new file mode 100644
index 00000000..fdf806a7
--- /dev/null
+++ b/test/problems/skel/output_validators/output_validator.py
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+import math
+import sys
+
+try:
+    # Do not use the default_output_validator.cpp, because it's wasteful to compile it for every test
+    if math.isclose(
+        4 * float(open(sys.argv[1]).read()) ** 0.5,
+        float(open(sys.argv[2]).read()),
+        rel_tol=1e-6,
+        abs_tol=1e-6,
+    ):
+        exit(42)
+    else:
+        print("WA")
+        exit(43)
+except Exception as e:
+    print(e)
+    exit(43)
diff --git a/test/problems/skel/problem.yaml b/test/problems/skel/problem.yaml
index 4112b4bc..099b9f31 100644
--- a/test/problems/skel/problem.yaml
+++ b/test/problems/skel/problem.yaml
@@ -8,7 +8,7 @@ uuid: 8ee7605a-9391-8727-1ee4-61028b8de953
 license: cc by-sa
 rights_owner: author
 # 'default', 'custom', or 'custom interactive'
-validation: default
+validation: custom  # Do not use the default_output_validator.cpp, because it's wasteful to compile it for every test
 
 # One or more of:
 # case_sensitive
@@ -16,7 +16,7 @@ validation: default
 # float_absolute_tolerance eps
 # float_relative_tolerance eps
 # float_tolerance eps
-validator_flags: float_tolerance 1e-6
+#validator_flags:
 
 # To change the time limit factors for problemtools/Kattis, use:
 limits:
diff --git a/test/problems/skel/submissions/accepted/hello.cpp b/test/problems/skel/submissions/accepted/hello.cpp
deleted file mode 100644
index 3d72cc78..00000000
--- a/test/problems/skel/submissions/accepted/hello.cpp
+++ /dev/null
@@ -1,11 +0,0 @@
-#include <iostream>
-#include <iomanip>
-#include <cmath>
-using namespace std;
-
-int main() {
-    int n;
-    cin >> n;
-    cout << fixed << setprecision(10) << 4*sqrt(n) << endl;
-    return 0;
-}
diff --git a/test/problems/skel/submissions/accepted/hello.py b/test/problems/skel/submissions/accepted/hello.py
new file mode 100644
index 00000000..f83966f3
--- /dev/null
+++ b/test/problems/skel/submissions/accepted/hello.py
@@ -0,0 +1,2 @@
+#!/usr/bin/env python3
+print(4 * int(input()) ** 0.5)
diff --git a/test/test_unit.py b/test/test_unit.py
index a3662980..947901f9 100644
--- a/test/test_unit.py
+++ b/test/test_unit.py
@@ -30,9 +30,9 @@ def setup_skel_problem(request):
 @pytest.mark.usefixtures('setup_skel_problem')
 class TestUnit:
     def test_memory(self):
-        shutil.copy('submissions/accepted/hello.cpp', 'submissions/run_time_error/hello.cpp')
+        shutil.copy('submissions/accepted/hello.py', 'submissions/run_time_error/hello.py')
         os.system(
-            'sed -i "s/cin >> n/auto huge = new int[100000000]; cin >> huge[42]; n = huge[42]/" submissions/run_time_error/hello.cpp'
+            'sed -i "s/print/list(range(int(1e8)));print/" submissions/run_time_error/hello.py'
         )
         tools.test('run --no-generate -m 256'.split())