diff --git a/clippy_lints/src/escape.rs b/clippy_lints/src/escape.rs
index c37efbd6e49d..52799ffbb454 100644
--- a/clippy_lints/src/escape.rs
+++ b/clippy_lints/src/escape.rs
@@ -4,6 +4,7 @@ use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
 use rustc::middle::expr_use_visitor::*;
 use rustc::middle::mem_categorization::{cmt_, Categorization};
 use rustc::ty::layout::LayoutOf;
+use rustc::ty::query::TyCtxtAt;
 use rustc::ty::{self, Ty};
 use rustc::util::nodemap::HirIdSet;
 use rustc::{declare_tool_lint, impl_lint_pass};
@@ -142,7 +143,10 @@ impl<'a, 'tcx> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {
                 if let StmtKind::Local(ref loc) = st.node {
                     if let Some(ref ex) = loc.init {
                         if let ExprKind::Box(..) = ex.node {
-                            if is_non_trait_box(cmt.ty) && !self.is_large_box(cmt.ty) {
+                            if is_non_trait_box(cmt.ty)
+                                && !self.is_large_box(cmt.ty)
+                                && !self.is_unsized_box(cmt.ty, cmt.span)
+                            {
                                 // let x = box (...)
                                 self.set.insert(consume_pat.hir_id);
                             }
@@ -205,4 +209,13 @@ impl<'a, 'tcx> EscapeDelegate<'a, 'tcx> {
             false
         }
     }
+
+    fn is_unsized_box(&self, ty: Ty<'tcx>, span: Span) -> bool {
+        if !ty.is_box() {
+            return false;
+        }
+
+        !ty.boxed_ty()
+            .is_sized(TyCtxtAt { tcx: self.cx.tcx, span }, self.cx.param_env)
+    }
 }
diff --git a/tests/ui/escape_analysis.rs b/tests/ui/escape_analysis.rs
index 78d332c7a31c..0c7641c30d82 100644
--- a/tests/ui/escape_analysis.rs
+++ b/tests/ui/escape_analysis.rs
@@ -109,6 +109,14 @@ fn nowarn_large_array() {
     }
 }
 
+fn nowarn_non_sized() {
+    let x: Box<[u32]> = box [1; 10000];
+    match &x {
+        // not moved
+        ref y => (),
+    }
+}
+
 /// ICE regression test
 pub trait Foo {
     type Item;
diff --git a/tests/ui/escape_analysis.stderr b/tests/ui/escape_analysis.stderr
index 3944acd87f28..a214f418c718 100644
--- a/tests/ui/escape_analysis.stderr
+++ b/tests/ui/escape_analysis.stderr
@@ -7,13 +7,13 @@ LL | fn warn_arg(x: Box<A>) {
    = note: `-D clippy::boxed-local` implied by `-D warnings`
 
 error: local variable doesn't need to be boxed here
-  --> $DIR/escape_analysis.rs:125:12
+  --> $DIR/escape_analysis.rs:133:12
    |
 LL | pub fn new(_needs_name: Box<PeekableSeekable<&()>>) -> () {}
    |            ^^^^^^^^^^^
 
 error: local variable doesn't need to be boxed here
-  --> $DIR/escape_analysis.rs:165:23
+  --> $DIR/escape_analysis.rs:173:23
    |
 LL |     fn closure_borrow(x: Box<A>) {
    |                       ^