diff --git a/src/flint.h.in b/src/flint.h.in
index dd24a3d068..c6b79d78e8 100644
--- a/src/flint.h.in
+++ b/src/flint.h.in
@@ -148,16 +148,22 @@ typedef struct __FLINT_FILE FLINT_FILE;
 # define FLINT_OPTIMIZE(x)
 #endif
 
-#if __STDC_VERSION__ < 201112L
+#ifdef __cplusplus
+# define FLINT_C_VERSION __cplusplus
+#else
+# define FLINT_C_VERSION __STDC_VERSION__
+#endif
+
+#if FLINT_C_VERSION < 201112L
 # error FLINT requires C11 or newer.
-#elif __STDC_VERSION__ < 202300L
+#elif FLINT_C_VERSION < 202300L
 # define FLINT_NORETURN _Noreturn
 #else
 # define FLINT_NORETURN noreturn
 #endif
 
 #if FLINT_USES_TLS
-# if __STDC_VERSION__ < 202300L
+# if FLINT_C_VERSION < 202300L
 #  define FLINT_TLS_PREFIX _Thread_local
 # else
 #  define FLINT_TLS_PREFIX thread_local