diff --git a/tuna.spec b/tuna.spec
index ebd2182..8881e66 100644
--- a/tuna.spec
+++ b/tuna.spec
@@ -3,7 +3,7 @@
 
 Name: tuna
 Version: 0.13.1
-Release: 3%{?dist}
+Release: 4%{?dist}
 License: GPLv2
 Summary: Application tuning GUI & command line utility
 Group: Applications/System
@@ -31,6 +31,7 @@ installed.
 Summary: Generic graphical signal plotting tool
 Group: Applications/System
 Requires: python-matplotlib
+Requires: python-matplotlib-gtk
 Requires: numpy
 Requires: pygtk2
 Requires: tuna = %{version}-%{release}
@@ -97,6 +98,9 @@ rm -rf %{buildroot}
 %doc docs/oscilloscope+tuna.pdf
 
 %changelog
+* Wed Nov 29 2017 Lubomir Rintel <lkundrak@v3.sk> - 0.13.1-4
+- Add a missing dependency for oscilloscope
+
 * Thu Jul 27 2017 Fedora Release Engineering <releng@fedoraproject.org> - 0.13.1-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_27_Mass_Rebuild