diff --git a/MozillaFirefox.changes b/MozillaFirefox.changes
index 02b1589d..68f9c82d 100644
--- a/MozillaFirefox.changes
+++ b/MozillaFirefox.changes
@@ -1,8 +1,8 @@
 -------------------------------------------------------------------
 Tue May 23 14:00:40 UTC 2017 - wr@rosenauer.org
 
-- remove -fno-inline-small-functions which breaks with gcc7
-  (boo#1040105)
+- remove -fno-inline-small-functions and explicitely optimize with
+  -O2 for openSUSE > 13.2/Leap 42 to work with gcc7 (boo#1040105)
 
 -------------------------------------------------------------------
 Mon May  8 08:28:17 UTC 2017 - wr@rosenauer.org
diff --git a/MozillaFirefox.spec b/MozillaFirefox.spec
index c9362258..3a05e69d 100644
--- a/MozillaFirefox.spec
+++ b/MozillaFirefox.spec
@@ -337,6 +337,10 @@ ac_add_options --enable-default-toolkit=cairo-gtk2
 %if 0%{?build_hardened}
 ac_add_options --enable-pie
 %endif
+# gcc7 (boo#104105)
+%if 0%{?suse_version} > 1320
+ac_add_options --enable-optimize="-g -O2"
+%endif
 %ifarch %ix86 %arm
 %if 0%{?suse_version} > 1230
 ac_add_options --disable-optimize