diff --git a/src/corelib/global/qfloat16.h b/src/corelib/global/qfloat16.h
index c2e5379eb42..59739fdcc12 100644
--- a/src/corelib/global/qfloat16.h
+++ b/src/corelib/global/qfloat16.h
@@ -333,7 +333,7 @@ template <> inline auto qHypot(qfloat16 x, qfloat16 y)
     return qfloat16(qHypot(float(x), float(y)));
 #endif
 }
-#if __cpp_lib_hypot >= 201603L // Expected to be true
+#if defined(__cpp_lib_hypot) && __cpp_lib_hypot >= 201603L // Expected to be true
 // If any are not qfloat16, convert each qfloat16 to float:
 /* (The following splits the some-but-not-all-qfloat16 cases up, using
    (X|Y|Z)&~(X&Y&Z) = X ? ~(Y&Z) : Y|Z = X&~(Y&Z) | ~X&Y | ~X&~Y&Z,
diff --git a/src/corelib/kernel/qmath.h b/src/corelib/kernel/qmath.h
index 18530714e0b..5e8d4fc2767 100644
--- a/src/corelib/kernel/qmath.h
+++ b/src/corelib/kernel/qmath.h
@@ -192,7 +192,7 @@ auto qHypot(Tx x, Ty y)
     return hypot(x, y);
 }
 
-#if __cpp_lib_hypot >= 201603L // Expected to be true
+#if defined(__cpp_lib_hypot) && __cpp_lib_hypot >= 201603L // Expected to be true
 template <typename Tx, typename Ty, typename Tz>
 auto qHypot(Tx x, Ty y, Tz z)
 {