diff --git a/sdk/lib/ucrt/math/_dtest.c b/sdk/lib/ucrt/math/_dtest.c
new file mode 100644
index 00000000000..34b03b52b36
--- /dev/null
+++ b/sdk/lib/ucrt/math/_dtest.c
@@ -0,0 +1,23 @@
+//
+// _dtest.c
+//
+//      Copyright (c) 2024 Timo Kreuzer
+//
+// Implementation of _dtest.
+//
+// SPDX-License-Identifier: MIT
+//
+
+#include <math.h>
+
+#ifdef _MSC_VER
+#pragma function(_dtest)
+#endif
+
+_Check_return_
+short
+__cdecl
+_dtest(_In_ double* _Px)
+{
+    return _dclass(*_Px);
+}
diff --git a/sdk/lib/ucrt/math/_fdtest.c b/sdk/lib/ucrt/math/_fdtest.c
new file mode 100644
index 00000000000..584d193191f
--- /dev/null
+++ b/sdk/lib/ucrt/math/_fdtest.c
@@ -0,0 +1,23 @@
+//
+// _fdtest.c
+//
+//      Copyright (c) 2024 Timo Kreuzer
+//
+// Implementation of _fdtest.
+//
+// SPDX-License-Identifier: MIT
+//
+
+#include <math.h>
+
+#ifdef _MSC_VER
+#pragma function(_fdtest)
+#endif
+
+_Check_return_
+short
+__cdecl
+_fdtest(_In_ float* _Px)
+{
+    return _fdclass(*_Px);
+}
diff --git a/sdk/lib/ucrt/math/math.cmake b/sdk/lib/ucrt/math/math.cmake
index 69f213e743f..06085f852f7 100644
--- a/sdk/lib/ucrt/math/math.cmake
+++ b/sdk/lib/ucrt/math/math.cmake
@@ -1,6 +1,8 @@
 
 list(APPEND UCRT_MATH_SOURCES
     math/_dclass.c
+    math/_dtest.c
     math/_fdclass.c
+    math/_fdtest.c
     math/matherr.cpp
 )