diff --git a/test/meson.build b/test/meson.build
index ade258e..2a6645f 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -7,6 +7,7 @@
   'signal': [stdplus_dep, gtest_main_dep],
   'util/cexec': [stdplus_dep, gtest_main_dep],
   'util/string': [stdplus_dep, gtest_main_dep],
+  'zstring': [stdplus_dep, gtest_main_dep],
   'zstring_view': [stdplus_dep, gtest_main_dep],
 }
 
diff --git a/test/zstring.cpp b/test/zstring.cpp
new file mode 100644
index 0000000..07ea1f1
--- /dev/null
+++ b/test/zstring.cpp
@@ -0,0 +1,103 @@
+#include <gtest/gtest.h>
+#include <iostream>
+#include <stdplus/zstring.hpp>
+#include <string>
+#include <string_view>
+
+using std::literals::string_literals::operator""s;
+using std::literals::string_view_literals::operator""sv;
+
+namespace stdplus
+{
+
+TEST(Zstring, Construct)
+{
+    auto str = "a\0"s;
+    const auto cstr = str;
+#ifdef NDEBUG
+    EXPECT_EQ("a", zstring(str));
+    EXPECT_EQ("a", const_zstring(str));
+    EXPECT_EQ("a", const_zstring(cstr));
+#else
+    EXPECT_THROW((zstring(str)), std::invalid_argument);
+    EXPECT_THROW((const_zstring(str)), std::invalid_argument);
+    EXPECT_THROW((const_zstring(cstr)), std::invalid_argument);
+#endif
+#ifdef NDEBUG
+    EXPECT_EQ("b", const_zstring("b\0"));
+#else
+    EXPECT_THROW(const_zstring("b\0"), std::invalid_argument);
+#endif
+    char as[] = "c";
+    EXPECT_EQ("c", zstring(as));
+    EXPECT_EQ("c", const_zstring(as));
+
+    std::cerr << const_zstring(as);
+}
+
+TEST(Zstring, NoTypeCoercion)
+{
+    char empty[] = "";
+    auto zs = zstring(empty);
+    auto czs = const_zstring("");
+
+    EXPECT_NE(zs, "\0");
+    EXPECT_NE("\0", zs);
+    EXPECT_NE(zs, "\0"sv);
+    EXPECT_NE("\0"sv, zs);
+    EXPECT_LT(zs, "\0"sv);
+    EXPECT_GT("\0"sv, zs);
+    EXPECT_NE(czs, "\0");
+    EXPECT_NE("\0", czs);
+    EXPECT_NE(czs, "\0"sv);
+    EXPECT_NE("\0"sv, czs);
+    EXPECT_LT(czs, "\0"sv);
+    EXPECT_GT("\0"sv, czs);
+
+    auto str = "\0"s;
+    EXPECT_NE(zs, str);
+    EXPECT_NE(str, zs);
+    EXPECT_LT(zs, str);
+    EXPECT_GT(str, zs);
+    EXPECT_NE(czs, str);
+    EXPECT_NE(str, czs);
+    EXPECT_LT(czs, str);
+    EXPECT_GT(str, czs);
+}
+
+TEST(Zstring, Comparison)
+{
+    char mut[] = "ac";
+    auto zs = zstring(mut);
+    auto czs = const_zstring("ac");
+
+#define test(cmp, rcmp, str)                                                   \
+    EXPECT_##cmp(zs, const_zstring(str));                                      \
+    EXPECT_##rcmp(const_zstring(str), zs);                                     \
+    EXPECT_##cmp(czs, const_zstring(str));                                     \
+    EXPECT_##rcmp(const_zstring(str), czs);                                    \
+    EXPECT_##cmp(zs, str);                                                     \
+    EXPECT_##rcmp(str, zs);                                                    \
+    EXPECT_##cmp(czs, str);                                                    \
+    EXPECT_##rcmp(str, czs);                                                   \
+    EXPECT_##cmp(zs, str##sv);                                                 \
+    EXPECT_##rcmp(str##sv, zs);                                                \
+    EXPECT_##cmp(czs, str##sv);                                                \
+    EXPECT_##rcmp(str##sv, czs);                                               \
+    EXPECT_##cmp(zs, str##s);                                                  \
+    EXPECT_##rcmp(str##s, zs);                                                 \
+    EXPECT_##cmp(czs, str##s);                                                 \
+    EXPECT_##rcmp(str##s, czs);                                                \
+    EXPECT_##cmp(zs, reinterpret_cast<const char*>(str));                      \
+    EXPECT_##rcmp(reinterpret_cast<const char*>(str), zs);                     \
+    EXPECT_##cmp(czs, reinterpret_cast<const char*>(str));                     \
+    EXPECT_##rcmp(reinterpret_cast<const char*>(str), czs)
+    test(EQ, EQ, "ac");
+    test(GT, LT, "a");
+    test(LT, GT, "acb");
+    test(LT, GT, "ad");
+    test(GT, LT, "ab");
+#undef test
+}
+
+} // namespace stdplus