diff --git a/firefox.spec b/firefox.spec
index c9b4833..a503c88 100644
--- a/firefox.spec
+++ b/firefox.spec
@@ -106,7 +106,13 @@ end}
 %global nodejs_build_req  nodejs
 
 %if 0%{?rhel} > 7 && 0%{?rhel} < 10
-%global use_gcc_ts        1
+  %global use_gcc_ts      1
+  %if 0%{?rhel} == 9 && %{rhel_minor_version} >= 6
+    # clang depends on gcc-toolset-14-gcc-c++
+    %global gts_version 14
+  %else
+    %global gts_version 13
+  %endif
 %endif
 
 %if 0%{?rhel} == 7
@@ -435,10 +441,12 @@ BuildRequires:  xorg-x11-server-Xvfb
 %endif
 
 %if 0%{?use_gcc_ts}
-BuildRequires: gcc-toolset-13-runtime
-BuildRequires: gcc-toolset-13-binutils
-BuildRequires: gcc-toolset-13-gcc
-BuildRequires: gcc-toolset-13-gcc-plugin-annobin
+BuildRequires: gcc-toolset-%{gts_version}-runtime
+BuildRequires: gcc-toolset-%{gts_version}-binutils
+BuildRequires: gcc-toolset-%{gts_version}-gcc
+BuildRequires: gcc-toolset-%{gts_version}-gcc-plugin-annobin
+# Do not explicitly require gcc-toolset-%{gts_version}-gcc-g++ instead fail
+# when clang is upgraded to depend on a later toolset and adjust version.
 %endif
 
 Requires:       mozilla-filesystem
@@ -1414,7 +1422,7 @@ function install_rpms_to_current_dir() {
 # Enable toolsets
 set +e
 %if 0%{?use_gcc_ts}
-source scl_source enable gcc-toolset-13
+source scl_source enable gcc-toolset-%{gts_version}
 %endif
 %if 0%{?use_dts}
 source scl_source enable devtoolset-%{dts_version}