diff --git a/src/common/HighScoresManager.cxx b/src/common/HighScoresManager.cxx
index 2cfdce762..24b3cbaf8 100644
--- a/src/common/HighScoresManager.cxx
+++ b/src/common/HighScoresManager.cxx
@@ -41,7 +41,6 @@
 */
 
 #include <cmath>
-#include <numbers>
 
 #include "OSystem.hxx"
 #include "PropsSet.hxx"
@@ -463,8 +462,8 @@ Int32 HighScoresManager::convert(Int32 val, uInt32 maxVal, bool isBCD,
   //maxVal += zeroBased ? 0 : 1;
   maxVal -= zeroBased ? 1 : 0;
   const Int32 bits = isBCD
-    ? ceil(log(maxVal) / std::numbers::ln10 * 4)
-    : ceil(log(maxVal) / std::numbers::ln2);
+    ? ceil(log(maxVal) / BSPF::ln10 * 4)
+    : ceil(log(maxVal) / BSPF::ln2);
 
   // limit to maxVal's bits
   val %= 1 << bits;
diff --git a/src/common/bspf.hxx b/src/common/bspf.hxx
index 9ac400217..bdad46e24 100644
--- a/src/common/bspf.hxx
+++ b/src/common/bspf.hxx
@@ -47,7 +47,6 @@ using uInt64 = uint64_t;
 #include <functional>
 #include <iomanip>
 #include <memory>
-#include <numbers>
 #include <string>
 #include <string_view>
 #include <charconv>
@@ -59,6 +58,11 @@ using uInt64 = uint64_t;
 #include <utility>
 #include <vector>
 
+// It seems not all C++20 implementations support this yet
+#if __has_include(<numbers>)
+  #include <numbers>
+#endif
+
 using std::cin;
 using std::cout;
 using std::cerr;
@@ -117,8 +121,21 @@ static const string EmptyString("");
 
 namespace BSPF
 {
+#if __has_include(<numbers>)
   static constexpr float PI_f = std::numbers::pi_v<float>;
   static constexpr double PI_d = std::numbers::pi_v<double>;
+  static constexpr double ln10 = std::numbers::ln10;
+  static constexpr double ln2 = std::numbers::ln2;
+#else
+  [[deprecated("C++20 implementation missing <numbers> support.")]]
+  static constexpr float PI_f = 3.141592653589793238462643383279502884F;
+  [[deprecated("C++20 implementation missing <numbers> support.")]]
+  static constexpr double PI_d = 3.141592653589793238462643383279502884;
+  [[deprecated("C++20 implementation missing <numbers> support.")]]
+  static constexpr double ln10 = 2.302585092994045684017991454684364208;
+  [[deprecated("C++20 implementation missing <numbers> support.")]]
+  static constexpr double ln2 = 0.693147180559945309417232121458176568;
+#endif
 
   // CPU architecture type
   // This isn't complete yet, but takes care of all the major platforms