diff --git a/clay.h b/clay.h
index f37dde3..5ccf0ac 100644
--- a/clay.h
+++ b/clay.h
@@ -21,6 +21,14 @@
 #ifndef CLAY_HEADER
 #define CLAY_HEADER
 
+#if !( \
+    (defined(__cplusplus) && __cplusplus >= 202002L) || \
+    (defined(__STDC__) && __STDC__ == 1 && defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || \
+    defined(_MSC_VER) \
+)
+#error "Clay requires C99, C++20, or MSVC"
+#endif
+
 #ifdef CLAY_WASM
 #define CLAY_WASM_EXPORT(name) __attribute__((export_name(name)))
 #else