diff --git a/srcpkgs/qt5/template b/srcpkgs/qt5/template
index 163b593db15..a8fb7c7b411 100644
--- a/srcpkgs/qt5/template
+++ b/srcpkgs/qt5/template
@@ -35,7 +35,8 @@ replaces="qt5-doc<5.6.0 qt5-quick1<5.6.0 qt5-quick1-devel<5.6.0 qt5-webkit<5.6.0
 
 # Work around SSLv3_{client,server}_method missing in libressl-2.3.3
 CFLAGS="-DOPENSSL_NO_PSK -DOPENSSL_NO_NEXTPROTONEG -DOPENSSL_NO_SSL3_METHOD"
-CXXFLAGS="${CFLAGS} -Wno-deprecated-declarations -fno-delete-null-pointer-checks"
+CXXFLAGS="${CFLAGS} -D_GLIBCXX_USE_C99_STDLIB=1 -D_GLIBCXX_USE_C99_STDIO=1"
+CXXFLAGS+=" -Wno-deprecated-declarations -fno-delete-null-pointer-checks"
 # Required for musl libc
 LDFLAGS="-pthread -ldl -fPIE"