diff --git a/clippy_lints/src/manual_slice_size_calculation.rs b/clippy_lints/src/manual_slice_size_calculation.rs
index 1de686dbc..429ee2637 100644
--- a/clippy_lints/src/manual_slice_size_calculation.rs
+++ b/clippy_lints/src/manual_slice_size_calculation.rs
@@ -40,11 +40,11 @@ declare_lint_pass!(ManualSliceSizeCalculation => [MANUAL_SLICE_SIZE_CALCULATION]
 
 impl<'tcx> LateLintPass<'tcx> for ManualSliceSizeCalculation {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
-        // Does not apply inside const because size_of_val is not cost in stable.
-        if !in_constant(cx, expr.hir_id)
-            && let ExprKind::Binary(ref op, left, right) = expr.kind
+        if let ExprKind::Binary(ref op, left, right) = expr.kind
             && BinOpKind::Mul == op.node
             && !expr.span.from_expansion()
+            // Does not apply inside const because size_of_val is not cost in stable.
+            && !in_constant(cx, expr.hir_id)
             && let Some(receiver) = simplify(cx, left, right)
         {
             let ctxt = expr.span.ctxt();