diff --git a/master/custom/builders.py b/master/custom/builders.py
index 907afe96..3f705d46 100644
--- a/master/custom/builders.py
+++ b/master/custom/builders.py
@@ -138,6 +138,17 @@
 
 # -- Stable Tier-3 builder ----------------------------------------------
 STABLE_BUILDERS_TIER_3 = [
+
+    # Linux s390x GCC
+    ("s390x RHEL9", "cstratak-rhel9-s390x", UnixBuild),
+    ("s390x RHEL9 Refleaks", "cstratak-rhel9-s390x", UnixRefleakBuild),
+    ("s390x RHEL9 LTO", "cstratak-rhel9-s390x", LTONonDebugUnixBuild),
+    ("s390x RHEL9 LTO + PGO", "cstratak-rhel9-s390x", LTOPGONonDebugBuild),
+    ("s390x RHEL8", "cstratak-rhel8-s390x", UnixBuild),
+    ("s390x RHEL8 Refleaks", "cstratak-rhel8-s390x", UnixRefleakBuild),
+    ("s390x RHEL8 LTO", "cstratak-rhel8-s390x", LTONonDebugUnixBuild),
+    ("s390x RHEL8 LTO + PGO", "cstratak-rhel8-s390x", LTOPGONonDebugBuild),
+
     # Linux ppc64le Clang
     ("PPC64LE Fedora Stable Clang", "cstratak-fedora-stable-ppc64le", ClangUnixBuild),
     ("PPC64LE Fedora Stable Clang Installed", "cstratak-fedora-stable-ppc64le", ClangUnixInstalledBuild),
diff --git a/master/custom/workers.py b/master/custom/workers.py
index 594acedd..03659fa6 100644
--- a/master/custom/workers.py
+++ b/master/custom/workers.py
@@ -144,6 +144,16 @@ def get_workers(settings):
             tags=['linux', 'unix', 'rhel', 'arm', 'arm64', 'aarch64'],
             parallel_tests=40,
         ),
+        cpw(
+            name="cstratak-rhel8-s390x",
+            tags=['linux', 'unix', 'rhel', 's390x'],
+            parallel_tests=10,
+        ),
+        cpw(
+            name="cstratak-rhel9-s390x",
+            tags=['linux', 'unix', 'rhel', 's390x'],
+            parallel_tests=10,
+        ),
         cpw(
             name="edelsohn-aix-ppc64",
             tags=['aix', 'unix', 'ppc64'],