diff --git a/kio-extras.spec b/kio-extras.spec
index 22a67e6..c38819a 100644
--- a/kio-extras.spec
+++ b/kio-extras.spec
@@ -58,6 +58,10 @@ BuildRequires:  qt5-qtsvg-devel
 %if 0%{?fedora} > 24
 %global htmlthumbnail 1
 BuildRequires:  qt5-qtwebengine-devel >= 5.7
+# work around possibly missing macro
+%{!?qt5_qtwebengine_arches:%global qt5_qtwebengine_arches %{ix86} x86_64 %{arm} aarch64 mips mipsel mips64el}
+# handled by qt5-srpm-macros, which defines %%qt5_qtwebengine_arches
+%{?qt5_qtwebengine_arches:ExclusiveArch: %{qt5_qtwebengine_arches}}
 %endif
 
 %if 0%{?tests}