diff --git a/libc/include/llvm-libc-macros/complex-macros.h b/libc/include/llvm-libc-macros/complex-macros.h
index e7b0edf96142d..db84bcd2b03b7 100644
--- a/libc/include/llvm-libc-macros/complex-macros.h
+++ b/libc/include/llvm-libc-macros/complex-macros.h
@@ -41,7 +41,11 @@
 #endif // LIBC_TYPES_HAS_CFLOAT16
 
 #ifdef LIBC_TYPES_HAS_CFLOAT128
+#ifdef LIBC_TYPES_CFLOAT128_IS_COMPLEX_LONG_DOUBLE
+#define CMPLXF128(r, i) __CMPLX(r, i, long double)
+#else
 #define CMPLXF128(r, i) __CMPLX(r, i, float128)
+#endif // LIBC_TYPES_CFLOAT128_IS_COMPLEX_LONG_DOUBLE
 #endif // LIBC_TYPES_HAS_CFLOAT128
 
 #endif // __STDC_NO_COMPLEX__