diff --git a/MozillaFirefox.changes b/MozillaFirefox.changes
index 5c798f3..8ae7793 100644
--- a/MozillaFirefox.changes
+++ b/MozillaFirefox.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Tue May  1 18:45:02 UTC 2018 - astieger@suse.com
+
+- fix build in openSUSE:Leap:42.3:Update, use gcc7
+
 -------------------------------------------------------------------
 Tue May  1 14:26:24 UTC 2018 - astieger@suse.com
 
diff --git a/MozillaFirefox.spec b/MozillaFirefox.spec
index 64650e1..593167d 100644
--- a/MozillaFirefox.spec
+++ b/MozillaFirefox.spec
@@ -58,7 +58,7 @@ BuildRequires:  autoconf213
 BuildRequires:  dbus-1-glib-devel
 BuildRequires:  fdupes
 %if 0%{?suse_version} <= 1320
-BuildRequires:  gcc5-c++
+BuildRequires:  gcc7-c++
 %else
 BuildRequires:  gcc-c++
 %endif
@@ -298,7 +298,7 @@ export MOZILLA_OFFICIAL=1
 export BUILD_OFFICIAL=1
 export MOZ_TELEMETRY_REPORTING=1
 %if 0%{?suse_version} <= 1320
-export CC=gcc-5
+export CC=gcc-7
 %endif
 export CFLAGS="%{optflags} -fno-strict-aliasing"
 # boo#986541: add -fno-delete-null-pointer-checks for gcc6