diff --git a/core/fxcrt/zip_unittest.cpp b/core/fxcrt/zip_unittest.cpp
index 211fd8d..40666c2 100644
--- a/core/fxcrt/zip_unittest.cpp
+++ b/core/fxcrt/zip_unittest.cpp
@@ -4,6 +4,7 @@
 
 #include <stdint.h>
 
+#include "core/fxcrt/notreached.h"
 #include "core/fxcrt/span.h"
 #include "core/fxcrt/zip.h"
 #include "testing/gmock/include/gmock/gmock.h"
@@ -12,6 +13,25 @@
 using ::testing::ElementsAreArray;
 
 namespace fxcrt {
+namespace {
+
+struct NoCopyNoMove {
+  NoCopyNoMove(int val) : value(val) {}
+  NoCopyNoMove(const NoCopyNoMove&) { NOTREACHED(); }
+  NoCopyNoMove(NoCopyNoMove&&) { NOTREACHED(); }
+  NoCopyNoMove& operator=(const NoCopyNoMove&) {
+    NOTREACHED();
+    return *this;
+  }
+  NoCopyNoMove& operator=(NoCopyNoMove&&) {
+    NOTREACHED();
+    return *this;
+  }
+
+  int value;
+};
+
+}  // namespace
 
 TEST(Zip, EmptyZip) {
   pdfium::span<const int> nothing;
@@ -87,6 +107,25 @@
   }
 }
 
+TEST(Zip, NoCopy) {
+  // Test that copies do not silently happen when zipping.
+  const NoCopyNoMove stuff1[] = {{1}, {2}, {3}};
+  const NoCopyNoMove expected[] = {{1}, {2}, {3}};
+  for (auto [in1, exp] : Zip(stuff1, expected)) {
+    EXPECT_EQ(exp.value, in1.value);
+  }
+}
+
+TEST(Zip, NoCopy3) {
+  // Test that copies do not silently happen when zipping.
+  const NoCopyNoMove stuff1[] = {{1}, {2}, {3}};
+  const NoCopyNoMove stuff2[] = {{4}, {5}, {6}};
+  const NoCopyNoMove expected[] = {{5}, {7}, {9}};
+  for (auto [in1, in2, exp] : Zip(stuff1, stuff2, expected)) {
+    EXPECT_EQ(exp.value, in1.value + in2.value);
+  }
+}
+
 TEST(Zip, BadArgumentsZip) {
   pdfium::span<const int> nothing;
   int stuff[] = {1, 2, 3};