diff --git a/openh264.spec b/openh264.spec
index a28f667..bc452ee 100644
--- a/openh264.spec
+++ b/openh264.spec
@@ -136,8 +136,10 @@ EOF
 
 mkdir -p $RPM_BUILD_ROOT%{_sysconfdir}/profile.d
 cat > $RPM_BUILD_ROOT%{_sysconfdir}/profile.d/gmpopenh264.sh << 'EOF'
-MOZ_GMP_PATH="${MOZ_GMP_PATH}${MOZ_GMP_PATH:+:}%{_libdir}/mozilla/plugins/gmp-gmpopenh264/system-installed"
-export MOZ_GMP_PATH
+if [[ ":$MOZ_GMP_PATH:" != *":%{_libdir}/mozilla/plugins/gmp-gmpopenh264/system-installed:"* ]]; then
+    MOZ_GMP_PATH="${MOZ_GMP_PATH}${MOZ_GMP_PATH:+:}%{_libdir}/mozilla/plugins/gmp-gmpopenh264/system-installed"
+    export MOZ_GMP_PATH
+fi
 EOF
 
 mkdir -p $RPM_BUILD_ROOT%{_datadir}/fish/vendor_conf.d