diff --git a/eb_hooks.py b/eb_hooks.py
index 81fbfc62..b2451392 100644
--- a/eb_hooks.py
+++ b/eb_hooks.py
@@ -2485,6 +2485,11 @@ def set_maximum(parallel, max_value):
         '*': (divide_by_factor, 2),
         CPU_TARGET_A64FX: (set_maximum, 1),
     },
+    'PETSc': {
+        # PETSc test suite can be quite memory hungry,
+        # so reduce parallelism when running tests (also impacts build)
+        '*': (divide_by_factor, 2),
+    },
     'QuantumESPRESSO': {
         CPU_TARGET_A64FX: (set_maximum, 6),
     },