diff --git a/tests/backend/riscv/test_preallocated.py b/tests/backend/riscv/test_preallocated.py
index 01bcaddd9e..2b97a8eb73 100644
--- a/tests/backend/riscv/test_preallocated.py
+++ b/tests/backend/riscv/test_preallocated.py
@@ -1,6 +1,7 @@
 from xdsl.backend.riscv.register_allocation import gather_allocated
 from xdsl.builder import Builder
 from xdsl.dialects import riscv, riscv_func
+from xdsl.dialects.builtin import SymbolRefAttr
 
 
 def test_gather_allocated():
@@ -56,3 +57,17 @@ def multiple_preallocated_body() -> None:
     )
 
     assert len(pa_regs) == 2
+
+    @Builder.implicit_region
+    def func_call_preallocated_body() -> None:
+        reg1 = riscv.IntRegisterType.unallocated()
+        v1 = riscv.GetRegisterOp(reg1).res
+        v2 = riscv.GetRegisterOp(riscv.Registers.S0).res
+        riscv_func.CallOp(SymbolRefAttr("hello"), (v1, v2), ())
+
+    pa_regs = gather_allocated(
+        riscv_func.FuncOp("foo", func_call_preallocated_body, ((), ()))
+    )
+
+    assert len(pa_regs) == 36
+    assert riscv.Registers.S0 in pa_regs
diff --git a/xdsl/backend/riscv/register_allocation.py b/xdsl/backend/riscv/register_allocation.py
index 7704b2943d..43fc29e01b 100644
--- a/xdsl/backend/riscv/register_allocation.py
+++ b/xdsl/backend/riscv/register_allocation.py
@@ -4,7 +4,7 @@
 from ordered_set import OrderedSet
 
 from xdsl.backend.riscv.register_queue import RegisterQueue
-from xdsl.dialects import riscv_func, riscv_scf, riscv_snitch
+from xdsl.dialects import riscv, riscv_func, riscv_scf, riscv_snitch
 from xdsl.dialects.riscv import (
     FloatRegisterType,
     IntRegisterType,
@@ -26,6 +26,15 @@ def gather_allocated(func: riscv_func.FuncOp) -> set[RISCVRegisterType]:
         if not isinstance(op, RISCVAsmOperation):
             continue
 
+        if isinstance(op, riscv_func.CallOp):
+            # These registers are not guaranteed to hold the same values when the callee
+            # returns, according to the RISC-V calling convention.
+            # https://riscv.org/wp-content/uploads/2015/01/riscv-calling.pdf
+            allocated.update(riscv.Registers.A)
+            allocated.update(riscv.Registers.T)
+            allocated.update(riscv.Registers.FA)
+            allocated.update(riscv.Registers.FT)
+
         for param in chain(op.operands, op.results):
             if isinstance(param.type, RISCVRegisterType) and param.type.is_allocated:
                 if not param.type.register_name.startswith("j"):