diff --git a/tests/src/choose_classic_markers.cpp b/tests/src/choose_classic_markers.cpp
index 3a78a5d..6a5cef9 100644
--- a/tests/src/choose_classic_markers.cpp
+++ b/tests/src/choose_classic_markers.cpp
@@ -1,5 +1,4 @@
 #include <gtest/gtest.h>
-#include "custom_parallel.h"
 
 #include "singlepp/choose_classic_markers.hpp"
 #include "tatami/tatami.hpp"
diff --git a/tests/src/classify_integrated.cpp b/tests/src/classify_integrated.cpp
index a18fc03..d945290 100644
--- a/tests/src/classify_integrated.cpp
+++ b/tests/src/classify_integrated.cpp
@@ -1,5 +1,4 @@
 #include <gtest/gtest.h>
-#include "custom_parallel.h"
 
 #include "singlepp/classify_integrated.hpp"
 #include "singlepp/classify_single.hpp"
diff --git a/tests/src/classify_single.cpp b/tests/src/classify_single.cpp
index be3b9e4..78ceab0 100644
--- a/tests/src/classify_single.cpp
+++ b/tests/src/classify_single.cpp
@@ -1,5 +1,4 @@
 #include <gtest/gtest.h>
-#include "custom_parallel.h"
 
 #include "singlepp/classify_single.hpp"
 #include "tatami/tatami.hpp"
diff --git a/tests/src/custom_parallel.h b/tests/src/custom_parallel.h
deleted file mode 100644
index 940016a..0000000
--- a/tests/src/custom_parallel.h
+++ /dev/null
@@ -1,32 +0,0 @@
-#ifndef CUSTOM_PARALLEL_H
-#define CUSTOM_PARALLEL_H
-#ifdef TEST_SINGLEPP_CUSTOM_PARALLEL
-
-#include <cmath>
-#include <vector>
-#include <thread>
-
-template<class Function>
-void singlepp_parallelize(Function f, size_t n, int nthreads) {
-    size_t jobs_per_worker = std::ceil(static_cast<double>(n) / nthreads);
-    size_t start = 0;
-    std::vector<std::thread> jobs;
-    jobs.reserve(nthreads);
-
-    for (int w = 0; w < nthreads; ++w) {
-        size_t end = std::min(n, start + jobs_per_worker);
-        if (start >= end) {
-            break;
-        }
-        jobs.emplace_back(f, w, start, end - start);
-        start += jobs_per_worker;
-    }
-
-    for (auto& job : jobs) {
-        job.join();
-    }
-}
-
-#define SINGLEPP_CUSTOM_PARALLEL singlepp_parallelize
-#endif
-#endif