diff --git a/newton/_src/solvers/implicit_mpm/solve_rheology.py b/newton/_src/solvers/implicit_mpm/solve_rheology.py
index d3f0abe6cb..ef59e493ea 100644
--- a/newton/_src/solvers/implicit_mpm/solve_rheology.py
+++ b/newton/_src/solvers/implicit_mpm/solve_rheology.py
@@ -1123,6 +1123,8 @@ def _register_temp(temp):
         compliance_mat_diagonal = None
     else:
         compliance_mat_diagonal = _register_temp(fem.borrow_temporary(temporary_store, shape=stress.shape, dtype=mat66))
+        # TODO: Remove .zero_() workaround once Newton uses warp_lang-1.12.0.dev20260113 or newer.
+        compliance_mat_diagonal.zero_()
         sp.bsr_get_diag(compliance_mat, out=compliance_mat_diagonal)
 
     # Project initial stress on yield surface