diff --git a/lib/compress.js b/lib/compress.js
index 3745b764..4235617d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -6934,7 +6934,9 @@ Compressor.prototype.compress = function(node) {
                     }
                     var argnames = node.argnames;
                     var rest = node.rest;
+                    var after = false, before = false;
                     if (rest) {
+                        before = true;
                         if (!args || spread < argnames.length || rest instanceof AST_SymbolFunarg) {
                             rest = rest.transform(trimmer);
                         } else {
@@ -6947,8 +6949,7 @@ Compressor.prototype.compress = function(node) {
                             args.length = argnames.length;
                             if (trimmed.value.elements.length) [].push.apply(args, trimmed.value.elements);
                         }
-                        if (rest instanceof AST_Destructured && !rest.rest
-                            && (!node.uses_arguments || tt.has_directive("use strict"))) {
+                        if (rest instanceof AST_Destructured && !rest.rest) {
                             if (rest instanceof AST_DestructuredArray) {
                                 if (rest.elements.length == 0) rest = null;
                             } else if (rest.properties.length == 0) {
@@ -6956,7 +6957,10 @@ Compressor.prototype.compress = function(node) {
                             }
                         }
                         node.rest = rest;
-                        if (rest) trim = false;
+                        if (rest) {
+                            trim = false;
+                            after = true;
+                        }
                     }
                     var default_length = trim ? -1 : node.length();
                     for (var i = argnames.length; --i >= 0;) {
@@ -6973,29 +6977,43 @@ Compressor.prototype.compress = function(node) {
                                 sym.unused = true;
                             }
                         } else {
+                            before = true;
                             var funarg;
                             if (!args || spread < i) {
                                 funarg = sym.transform(trimmer);
                             } else {
-                                funarg = trim_destructured(sym, args[i], function(node) {
+                                var trimmed = trim_destructured(sym, args[i], function(node) {
                                     return node.definition().id in in_use_ids ? node : null;
-                                }, !node.uses_arguments, sym).name;
+                                }, !node.uses_arguments, sym);
+                                funarg = trimmed.name;
+                                if (trimmed.value) args[i] = trimmed.value;
                             }
                             if (funarg) {
                                 trim = false;
+                                argnames[i] = funarg;
+                                if (!after) after = !(funarg instanceof AST_SymbolFunarg);
                             } else if (trim) {
                                 log_default(sym, "Dropping unused default argument {name}");
                                 argnames.pop();
                             } else if (i > default_length) {
                                 log_default(sym, "Dropping unused default argument assignment {name}");
-                                if (sym.name instanceof AST_SymbolFunarg) sym.name.unused = true;
+                                if (sym.name instanceof AST_SymbolFunarg) {
+                                    sym.name.unused = true;
+                                } else {
+                                    after = true;
+                                }
                                 argnames[i] = sym.name;
                             } else {
                                 log_default(sym, "Dropping unused default argument value {name}");
+                                argnames[i] = sym = sym.clone();
                                 sym.value = make_node(AST_Number, sym, { value: 0 });
+                                after = true;
                             }
                         }
                     }
+                    if (before && !after && node.uses_arguments && !tt.has_directive("use strict")) {
+                        node.rest = make_node(AST_DestructuredArray, node, { elements: [] });
+                    }
                     fns_with_marked_args.push(node);
                 }
             }
@@ -7555,6 +7573,7 @@ Compressor.prototype.compress = function(node) {
                 var value = node.value.drop_side_effect_free(compressor);
                 if (!value) return null;
                 log(node.name, "Side effects in default value of unused variable {name}");
+                node = node.clone();
                 node.name.unused = null;
                 node.value = value;
             }
@@ -7632,6 +7651,7 @@ Compressor.prototype.compress = function(node) {
                     drop = save_drop;
                     if (values && newValues) {
                         fill_holes(value, newValues);
+                        value = value.clone();
                         value.elements = newValues;
                     }
                     if (!node.rest && (value instanceof AST_Array
@@ -7665,20 +7685,25 @@ Compressor.prototype.compress = function(node) {
                         drop = false;
                         value = value.fixed_value();
                     }
-                    var prop_keys, prop_map;
+                    var prop_keys, prop_map, values;
                     if (value instanceof AST_Object) {
                         prop_keys = [];
                         prop_map = new Dictionary();
-                        value.properties.forEach(function(prop, index) {
-                            if (prop instanceof AST_Spread) return prop_map = false;
-                            var key = prop.key;
-                            if (key instanceof AST_Node) key = key.evaluate(compressor, true);
-                            if (key instanceof AST_Node) {
+                        values = value.properties.map(function(prop, index) {
+                            prop = prop.clone();
+                            if (prop instanceof AST_Spread) {
                                 prop_map = false;
-                            } else if (prop_map && !(prop instanceof AST_ObjectSetter)) {
-                                prop_map.set(key, prop);
+                            } else {
+                                var key = prop.key;
+                                if (key instanceof AST_Node) key = key.evaluate(compressor, true);
+                                if (key instanceof AST_Node) {
+                                    prop_map = false;
+                                } else if (prop_map && !(prop instanceof AST_ObjectSetter)) {
+                                    prop_map.set(key, prop);
+                                }
+                                prop_keys[index] = key;
                             }
-                            prop_keys[index] = key;
+                            return prop;
                         });
                     }
                     if (node.rest) {
@@ -7743,27 +7768,30 @@ Compressor.prototype.compress = function(node) {
                     });
                     value = save_value;
                     drop = save_drop;
-                    if (drop_keys && prop_keys) value.properties = List(value.properties, function(prop, index) {
-                        if (prop instanceof AST_Spread) return prop;
-                        var key = prop_keys[index];
-                        if (key instanceof AST_Node) return prop;
-                        if (drop_keys.has(key)) {
-                            var mapped = drop_keys.get(key);
-                            if (!mapped) return prop;
-                            if (mapped === prop) return prop_map.get(key) || List.skip;
-                        } else if (node.rest) {
-                            return prop;
-                        }
-                        var trimmed = prop.value.drop_side_effect_free(compressor);
-                        if (trimmed) {
-                            prop.value = trimmed;
-                            return prop;
-                        }
-                        return retain_key(prop) ? make_node(AST_ObjectKeyVal, prop, {
-                            key: prop.key,
-                            value: make_node(AST_Number, prop, { value: 0 }),
-                        }) : List.skip;
-                    });
+                    if (drop_keys && prop_keys) {
+                        value = value.clone();
+                        value.properties = List(values, function(prop, index) {
+                            if (prop instanceof AST_Spread) return prop;
+                            var key = prop_keys[index];
+                            if (key instanceof AST_Node) return prop;
+                            if (drop_keys.has(key)) {
+                                var mapped = drop_keys.get(key);
+                                if (!mapped) return prop;
+                                if (mapped === prop) return prop_map.get(key) || List.skip;
+                            } else if (node.rest) {
+                                return prop;
+                            }
+                            var trimmed = prop.value.drop_side_effect_free(compressor);
+                            if (trimmed) {
+                                prop.value = trimmed;
+                                return prop;
+                            }
+                            return retain_key(prop) ? make_node(AST_ObjectKeyVal, prop, {
+                                key: prop.key,
+                                value: make_node(AST_Number, prop, { value: 0 }),
+                            }) : List.skip;
+                        });
+                    }
                     if (value && !node.rest) switch (properties.length) {
                       case 0:
                         if (node === root) break;
diff --git a/test/compress/default-values.js b/test/compress/default-values.js
index 9878820c..f0859749 100644
--- a/test/compress/default-values.js
+++ b/test/compress/default-values.js
@@ -2313,3 +2313,85 @@ issue_5444_3: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_5448_1: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(a = typeof console.log) {
+            do {
+                var b = [ ...a ];
+            } while (console.log("PASS"));
+        })();
+    }
+    expect: {
+        (function(a = console.log) {
+            do {} while (console.log("PASS"));
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5448_2: {
+    options = {
+        keep_fargs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(a = typeof console) {
+            do {
+                var b = [ ...a ];
+            } while (console.log("PASS"));
+        })();
+    }
+    expect: {
+        (function(a = 0) {
+            do {} while (console.log("PASS"));
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5448_3: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var [ a = typeof console ] = [ void console.log("PASS") ];
+        var b = [ ...a ];
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5448_4: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var { p: a = typeof console } = { p: void console.log("PASS") };
+        var b = [ ...a ];
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
diff --git a/test/compress/destructured.js b/test/compress/destructured.js
index 847ab87c..2ef7acee 100644
--- a/test/compress/destructured.js
+++ b/test/compress/destructured.js
@@ -3020,6 +3020,7 @@ issue_5074_method_pure_getters: {
 issue_5085_1: {
     options = {
         evaluate: true,
+        passes: 2,
         reduce_vars: true,
         toplevel: true,
         unsafe: true,
@@ -3032,8 +3033,7 @@ issue_5085_1: {
     }
     expect: {
         var a = "PASS";
-        var b = [ 42 ][0];
-        b;
+        42;
         console.log(a);
     }
     expect_stdout: "PASS"
@@ -3043,6 +3043,7 @@ issue_5085_1: {
 issue_5085_2: {
     options = {
         evaluate: true,
+        passes: 2,
         reduce_vars: true,
         side_effects: true,
         unsafe: true,
@@ -3059,7 +3060,7 @@ issue_5085_2: {
     expect: {
         var a = "PASS";
         (function(b) {
-            b = [ 42 ][0];
+            0;
         })();
         console.log(a);
     }