diff --git a/openair1/PHY/TOOLS/tests/test_log2_approx.cpp b/openair1/PHY/TOOLS/tests/test_log2_approx.cpp
index 23cae706f6..c05540b61c 100644
--- a/openair1/PHY/TOOLS/tests/test_log2_approx.cpp
+++ b/openair1/PHY/TOOLS/tests/test_log2_approx.cpp
@@ -10,12 +10,28 @@ uint8_t log2_approx_ref(uint32_t x)
   return std::round(std::log2(x));
 }
 
-TEST(log2_approx_ref, complete)
+uint8_t log2_approx64_ref(unsigned long long int x)
+{
+  return std::round(std::log2(static_cast<long double>(x)));
+}
+
+TEST(log2_approx, complete)
 {
   for (uint32_t i = 0; i < UINT32_MAX; i++)
     EXPECT_EQ(log2_approx(i), log2_approx_ref(i));
 }
 
+TEST(log2_approx64, boundaries)
+{
+  for (long double i = 0; i < 64; i++) {
+    unsigned long long i2 = std::pow(2.0L, i + 0.5L);
+    for (unsigned long long j = -10; j <= 10; j++) {
+      unsigned long long x = i2 + j;
+      EXPECT_EQ(log2_approx64(x), log2_approx64_ref(x));
+    }
+  }
+}
+
 int main(int argc, char **argv)
 {
   logInit();