diff --git a/flang/lib/Lower/ConvertExprToHLFIR.cpp b/flang/lib/Lower/ConvertExprToHLFIR.cpp
--- a/flang/lib/Lower/ConvertExprToHLFIR.cpp
+++ b/flang/lib/Lower/ConvertExprToHLFIR.cpp
@@ -1259,9 +1259,28 @@
     hlfir::Entity entity, Fortran::lower::StatementContext &stmtCtx) {
   auto exv = Fortran::lower::translateToExtendedValue(
       loc, converter.getFirOpBuilder(), entity, stmtCtx);
-  if (fir::isa_trivial(fir::getBase(exv).getType()))
-    TODO(loc, "place trivial in memory");
-  return fir::factory::createBoxValue(converter.getFirOpBuilder(), loc, exv);
+  mlir::Value base = fir::getBase(exv);
+  fir::FirOpBuilder &builder = converter.getFirOpBuilder();
+
+  if (fir::isa_trivial(base.getType())) {
+    // place trivial in memory
+    mlir::Type ty = base.getType();
+    mlir::Operation *op = base.getDefiningOp();
+
+    // put alloca in entry block
+    auto insertPt = builder.saveInsertionPoint();
+    if (auto func = op->getParentOfType<mlir::func::FuncOp>()) {
+      mlir::Block *entryBlock = &func.getBlocks().front();
+      builder.setInsertionPointToStart(entryBlock);
+    }
+    mlir::Value ref = builder.create<fir::AllocaOp>(loc, ty);
+    builder.restoreInsertionPoint(insertPt);
+
+    builder.create<fir::StoreOp>(loc, base, ref);
+    exv = fir::ExtendedValue{ref};
+  }
+
+  return fir::factory::createBoxValue(builder, loc, exv);
 }
 fir::BoxValue Fortran::lower::convertExprToBox(
     mlir::Location loc, Fortran::lower::AbstractConverter &converter,
diff --git a/flang/test/Lower/HLFIR/intrinsic-subroutines.f90 b/flang/test/Lower/HLFIR/intrinsic-subroutines.f90
--- a/flang/test/Lower/HLFIR/intrinsic-subroutines.f90
+++ b/flang/test/Lower/HLFIR/intrinsic-subroutines.f90
@@ -12,3 +12,15 @@
 ! CHECK:  %[[VAL_2:.*]] = fir.call @_FortranACpuTime() fastmath<contract> : () -> f64
 ! CHECK:  %[[VAL_3:.*]] = fir.convert %[[VAL_2]] : (f64) -> f32
 ! CHECK:  fir.store %[[VAL_3]] to %[[VAL_1]]#1 : !fir.ref<f32>
+
+! check we can box a trivial value
+subroutine sumMask(s, a)
+  integer :: s
+  integer :: a(:)
+  s = sum(a, mask=.true.)
+endsubroutine
+! CHECK-LABEL: func.func @_QPsummask(
+! CHECK:      %[[ALLOC:.*]] = fir.alloca i1
+! CHECK:      %[[TRUE:.*]] = arith.constant true
+! CHECK-NEXT: fir.store %[[TRUE]] to %[[ALLOC]]
+! CHECK-NEXT: %[[BOX:.*]] = fir.embox %[[ALLOC]] : (!fir.ref<i1>) -> !fir.box<i1>