diff --git a/benchmarks/benchmark_utils.hpp b/benchmarks/benchmark_utils.hpp
index bf0c2cd..bd39b25 100644
--- a/benchmarks/benchmark_utils.hpp
+++ b/benchmarks/benchmark_utils.hpp
@@ -26,6 +26,9 @@ static void benchmark_sinf(benchmark::State &state) {
       reinterpret_cast<float *>(backend.allocate_memory(N * sizeof(float)));
   float *s =
       reinterpret_cast<float *>(backend.allocate_memory(N * sizeof(float)));
+  if (!x || !s) {
+    throw std::runtime_error("Buffer allocation failed");
+  }
   auto end = std::chrono::high_resolution_clock::now();
   state.counters["init_ms"] =
       std::chrono::duration_cast<std::chrono::microseconds>(end - start)
diff --git a/src/lookup_xsimd.cpp b/src/lookup_xsimd.cpp
index ab9ba65..18cf42d 100644
--- a/src/lookup_xsimd.cpp
+++ b/src/lookup_xsimd.cpp
@@ -78,7 +78,7 @@ template <std::size_t NR_SAMPLES> struct cosf_dispatcher {
       const float dx = a[i] - idx * lookup_table_.PI_FRAC;
       const float dx2 = dx * dx;
       const float dx3 = dx2 * dx;
-      const float dx4 = dx3 * dx;
+      const float dx4 = dx2 * dx2;
       const float cosdx =
           1.0f - lookup_table_.TERM2 * dx2 + lookup_table_.TERM4 * dx4;
       const float sindx = dx - lookup_table_.TERM3 * dx3;
@@ -138,7 +138,7 @@ template <std::size_t NR_SAMPLES> struct sinf_dispatcher {
       const float dx = a[i] - idx * lookup_table_.PI_FRAC;
       const float dx2 = dx * dx;
       const float dx3 = dx2 * dx;
-      const float dx4 = dx3 * dx;
+      const float dx4 = dx2 * dx2;
       const float cosdx =
           1.0f - lookup_table_.TERM2 * dx2 + lookup_table_.TERM4 * dx4;
       const float sindx = dx - lookup_table_.TERM3 * dx3;
@@ -202,7 +202,7 @@ template <std::size_t NR_SAMPLES> struct sin_cosf_dispatcher {
       const float dx = a[i] - idx * lookup_table_.PI_FRAC;
       const float dx2 = dx * dx;
       const float dx3 = dx2 * dx;
-      const float dx4 = dx3 * dx;
+      const float dx4 = dx2 * dx2;
       const float cosdx =
           1.0f - lookup_table_.TERM2 * dx2 + lookup_table_.TERM4 * dx4;
       const float sindx = dx - lookup_table_.TERM3 * dx3;