diff --git a/core/include/kernel_defines.h b/core/include/kernel_defines.h
index 12f3ea410b..5bb77a0108 100644
--- a/core/include/kernel_defines.h
+++ b/core/include/kernel_defines.h
@@ -236,6 +236,27 @@ extern "C" {
 #define DECLARE_CONSTANT(identifier, const_expr) \
     WITHOUT_PEDANTIC(enum { identifier = const_expr };)
 
+#if DOXYGEN
+/**
+ * @brief   Check if given variable / expression is detected as compile time
+ *          constant
+ * @note    This might return 0 on compile time constant expressions if the
+ *          compiler is not able to prove the constness at the given level
+ *          of optimization.
+ * @details This will return 0 if the used compiler does not support this
+ * @warning This is intended for internal use only
+ *
+ * This allows providing two different implementations in C, with one being
+ * more efficient if constant folding is used.
+ */
+#define IS_CT_CONSTANT(expr) <IMPLEMENTATION>
+#elif defined(__GNUC__)
+/* both clang and gcc (which both define __GNUC__) support this */
+#define IS_CT_CONSTANT(expr) __builtin_constant_p(expr)
+#else
+#define IS_CT_CONSTANT(expr) 0
+#endif
+
 /**
  * @cond INTERNAL
  */
diff --git a/tests/unittests/tests-kernel_defines/tests-kernel_defines.c b/tests/unittests/tests-kernel_defines/tests-kernel_defines.c
index 6d63ee981c..5ea45f820d 100644
--- a/tests/unittests/tests-kernel_defines/tests-kernel_defines.c
+++ b/tests/unittests/tests-kernel_defines/tests-kernel_defines.c
@@ -77,12 +77,36 @@ static void test_declare_constant(void)
     static_assert(sizeof(test_array) == 3, "test_array should be 3 bytes long");
 }
 
+#ifdef BOARD_NATIVE
+/* native compiles with -Og, which does not automatically inline functions.
+ * We just turn the function into a macro to get the test also passing on
+ * native */
+#define magic_computation(...) (unsigned)(42U * 3.14159 / 1337U)
+#else
+static unsigned magic_computation(void)
+{
+    return (unsigned)(42U * 3.14159 / 1337U);
+}
+#endif
+
+static void test_is_compile_time_constant(void)
+{
+    /* These test might fail on non-GCC-non-clang compilers. We don't support
+     * any of those (yet), but this test might need adaption in the future */
+    unsigned actual_constant = magic_computation();
+    volatile unsigned not_a_constant = actual_constant;
+
+    TEST_ASSERT(IS_CT_CONSTANT(actual_constant));
+    TEST_ASSERT(!IS_CT_CONSTANT(not_a_constant));
+}
+
 Test *tests_kernel_defines_tests(void)
 {
     EMB_UNIT_TESTFIXTURES(fixtures) {
         new_TestFixture(test_kernel_version),
         new_TestFixture(test_index_of),
         new_TestFixture(test_declare_constant),
+        new_TestFixture(test_is_compile_time_constant),
     };
 
     EMB_UNIT_TESTCALLER(kernel_defines_tests, NULL, NULL, fixtures);