diff --git a/MozillaThunderbird.changes b/MozillaThunderbird.changes
index 4dc7f6c..8a1b9f2 100644
--- a/MozillaThunderbird.changes
+++ b/MozillaThunderbird.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Sun Jun  4 07:31:01 UTC 2017 - wr@rosenauer.org
+
+- remove legacy -Os optimization breaking gcc7/i586 (boo#1042090)
+
 -------------------------------------------------------------------
 Thu Jun  1 06:09:23 UTC 2017 - wr@rosenauer.org
 
diff --git a/MozillaThunderbird.spec b/MozillaThunderbird.spec
index 858cce9..2b0977a 100644
--- a/MozillaThunderbird.spec
+++ b/MozillaThunderbird.spec
@@ -223,9 +223,6 @@ export CFLAGS="$RPM_OPT_FLAGS -fno-strict-aliasing"
 %if 0%{?suse_version} > 1320
 export CFLAGS="$CFLAGS -fno-delete-null-pointer-checks"
 %endif
-%if %{with mozilla_tb_optimize_for_size}
-export CFLAGS="$CFLAGS -Os"
-%endif
 %ifarch ppc64 ppc64le
 export CFLAGS="$CFLAGS -mminimal-toc"
 %endif