diff --git a/lib/compress.js b/lib/compress.js
index 41e5d4cd..19b58fc4 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3416,9 +3416,15 @@ Compressor.prototype.compress = function(node) {
                 if (def.references.length - def.replaced == referenced) return true;
                 if (!def.fixed) return false;
                 if (!lhs.fixed) return false;
-                if (def.references.filter(function(ref) {
-                    return ref.fixed === lhs.fixed;
-                }).length != referenced) return false;
+                var matched = 0;
+                if (!all(def.references, function(ref, index) {
+                    var fixed = ref.fixed;
+                    if (!fixed) return false;
+                    if (fixed.to_binary || fixed.to_prefix) return false;
+                    if (fixed === lhs.fixed) matched++;
+                    return true;
+                })) return false;
+                if (matched != referenced) return false;
                 verify_ref = true;
                 return true;
             }
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index 4c705abc..16dcd81d 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -10000,3 +10000,55 @@ issue_5568: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5638_1: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var log = console.log;
+        var a = { foo: 42 }, b;
+        for (var k in a) {
+            b = a[k];
+            log(k || b, b++);
+        }
+    }
+    expect: {
+        var log = console.log;
+        var a = { foo: 42 }, b;
+        for (var k in a) {
+            b = a[k];
+            log(k || b, b++);
+        }
+    }
+    expect_stdout: "foo 42"
+}
+
+issue_5638_2: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var log = console.log;
+        var a = { foo: 6 }, b;
+        for (var k in a) {
+            b = a[k];
+            log(k || b, b *= 7);
+        }
+    }
+    expect: {
+        var log = console.log;
+        var a = { foo: 6 }, b;
+        for (var k in a) {
+            b = a[k];
+            log(k || b, b *= 7);
+        }
+    }
+    expect_stdout: "foo 42"
+}
diff --git a/test/compress/hoist_vars.js b/test/compress/hoist_vars.js
index d0a73d49..73f4a69f 100644
--- a/test/compress/hoist_vars.js
+++ b/test/compress/hoist_vars.js
@@ -701,3 +701,57 @@ issue_5626: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5638_1: {
+    options = {
+        collapse_vars: true,
+        hoist_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var log = console.log;
+        var o = { foo: 42 };
+        for (var k in o) {
+            var v = o[k];
+            log(k || v, v++);
+        }
+    }
+    expect: {
+        var log, o, k, v;
+        log = console.log;
+        for (k in o = { foo: 42 }) {
+            v = o[k];
+            log(k || v, v++);
+        }
+    }
+    expect_stdout: "foo 42"
+}
+
+issue_5638_2: {
+    options = {
+        collapse_vars: true,
+        hoist_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var log = console.log;
+        var o = { foo: 6 };
+        for (var k in o) {
+            var v = o[k];
+            log(k || v, v *= 7);
+        }
+    }
+    expect: {
+        var log, o, k, v;
+        log = console.log;
+        for (k in o = { foo: 6 }) {
+            v = o[k];
+            log(k || v, v *= 7);
+        }
+    }
+    expect_stdout: "foo 42"
+}