diff --git a/tests/Main.c b/tests/Main.c
index da7f453..9dc7a5a 100644
--- a/tests/Main.c
+++ b/tests/Main.c
@@ -35,6 +35,7 @@ int main(int argc, char *argv[])
     {"ReaderNull", ReaderNull_tests},
     {"Writer", Writer_tests},
     {"WriterGKC", WriterGKC_tests},
+    {"ReaderWriter", ReaderWriter_tests},
   };
 
   NOT_USED(argc);
diff --git a/tests/RWTest.c b/tests/RWTest.c
new file mode 100644
index 0000000..08b1193
--- /dev/null
+++ b/tests/RWTest.c
@@ -0,0 +1,200 @@
+/*
+ * StreamLib test: Reader/Writer interoperability
+ * Copyright (C) 2026 Christopher Bazley
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ */
+
+/* ISO library headers */
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/* StreamLib headers */
+#include "ReaderGKey.h"
+#include "ReaderMem.h"
+#include "ReaderRaw.h"
+#include "WriterGKey.h"
+#include "WriterMem.h"
+#include "WriterRaw.h"
+#ifdef ACORN_FLEX
+#include "ReaderFlex.h"
+#include "WriterFlex.h"
+#endif
+
+/* Local headers */
+#include "Tests.h"
+
+enum {
+  MaxHistoryLog2 = 12,
+  RandomSeed = 0x5eed,
+  DataSize = 65536,
+  MaxChunkSize = 1024
+};
+
+/* Exercise any compatible pair of initialized streams. Destroying the writer
+ before reading is important because some writers buffer their output. */
+typedef void InitReaderFn(Reader *reader, void *stream, unsigned int history_log2);
+
+static void test_random_data(Writer *const writer,
+                             InitReaderFn *const init_reader,
+                             void *const stream,
+                             const unsigned int history_log2)
+{
+  size_t chunk_size = 0;
+
+  srand(RandomSeed);
+
+  for (size_t done = 0; done < DataSize; done += chunk_size) {
+    chunk_size = 1 + (size_t)rand() % (1 + MaxChunkSize);
+    if (chunk_size > DataSize - done) {
+      chunk_size = DataSize - done;
+    }
+
+    unsigned char expected[MaxChunkSize];
+
+    for (size_t i = 0; i < chunk_size; ++i) {
+      expected[i] = (unsigned char)(rand() & UCHAR_MAX);
+    }
+
+    assert(writer_fwrite(expected, 1, chunk_size, writer) == chunk_size);
+  }
+  assert(!writer_ferror(writer));
+  assert(writer_destroy(writer) == DataSize);
+
+  Reader reader;
+  init_reader(&reader, stream, history_log2);
+
+  srand(RandomSeed);
+  
+  for (size_t done = 0; done < DataSize; done += chunk_size) {
+    chunk_size = 1 + (size_t)rand() % (1 + MaxChunkSize);
+    if (chunk_size > DataSize - done) {
+      chunk_size = DataSize - done;
+    }
+
+    unsigned char actual[MaxChunkSize];
+
+    assert(reader_fread(actual, 1, chunk_size, &reader) == chunk_size);
+    for (size_t i = 0; i < chunk_size; ++i) {
+      assert(actual[i] == (unsigned char)(rand() & UCHAR_MAX));
+    }
+  }
+
+  assert(!reader_ferror(&reader));
+  assert(reader_fgetc(&reader) == EOF);
+  assert(reader_feof(&reader));
+  reader_destroy(&reader);
+}
+
+static void init_raw_reader(Reader *const reader, void *const stream,
+                            const unsigned int history_log2)
+{
+  NOT_USED(history_log2);
+  FILE *const file = stream;
+  assert(!fseek(file, 0, SEEK_SET));
+  reader_raw_init(reader, file);
+}
+
+static void init_gkey_reader(Reader *const reader, void *const stream,
+                             const unsigned int history_log2)
+{
+  FILE *const file = stream;
+  assert(!fseek(file, 0, SEEK_SET));
+  assert(reader_gkey_init(reader, history_log2, file));
+}
+
+static void init_mem_reader(Reader *const reader, void *const stream,
+                            const unsigned int history_log2)
+{
+  NOT_USED(history_log2);
+  assert(reader_mem_init(reader, stream, DataSize));
+}
+
+static void test_raw(void)
+{
+  Writer writer;
+  _Optional FILE *const file = tmpfile();
+  assert(file != NULL);
+
+  writer_raw_init(&writer, &*file);
+  test_random_data(&writer, init_raw_reader, &*file, 0);
+
+  assert(!fclose(&*file));
+}
+
+static void test_gkey(void)
+{
+  for (unsigned int history_log2 = 0; history_log2 < MaxHistoryLog2; ++history_log2)
+  {
+    FILE *const file = tmpfile();
+    assert(file != NULL);
+
+    Writer writer;
+    assert(writer_gkey_init(&writer, history_log2, 0, file));
+    test_random_data(&writer, init_gkey_reader, file, history_log2);
+
+    assert(!fclose(file));
+  }
+}
+
+static void test_mem(void)
+{
+  Writer writer;
+  _Optional unsigned char *const buffer = malloc(DataSize);
+  assert(buffer != NULL);
+
+  assert(writer_mem_init(&writer, &*buffer, DataSize));
+  test_random_data(&writer, init_mem_reader, &*buffer, 0);
+
+  free(buffer);
+}
+
+#ifdef ACORN_FLEX
+static void init_flex_reader(Reader *const reader, void *const stream,
+                             const unsigned int history_log2)
+{
+  NOT_USED(history_log2);
+  reader_flex_init(reader, stream);
+}
+
+static void test_flex(void)
+{
+  Writer writer;
+  void *anchor = NULL;
+
+  assert(flex_alloc(&anchor, 0));
+  writer_flex_init(&writer, &anchor);
+  test_random_data(&writer, init_flex_reader, &anchor);
+
+  flex_free(&anchor);
+}
+#endif
+
+void ReaderWriter_tests(void)
+{
+  static const struct {
+    const char *test_name;
+    void (*test_func)(void);
+  } tests[] = {
+    {"Write raw and read back", test_raw},
+    {"Write compressed and read back", test_gkey},
+    {"Write to memory and read back", test_mem},
+#ifdef ACORN_FLEX
+    {"Write to Flex and read back", test_flex},
+#endif
+  };
+
+  for (size_t i = 0; i < ARRAY_SIZE(tests); ++i) {
+    printf("Test %zu/%zu : %s\n", 1 + i, ARRAY_SIZE(tests),
+           tests[i].test_name);
+
+    Fortify_EnterScope();
+    tests[i].test_func();
+    Fortify_LeaveScope();
+  }
+}
+
diff --git a/tests/Tests.h b/tests/Tests.h
index d619086..cfd5c46 100644
--- a/tests/Tests.h
+++ b/tests/Tests.h
@@ -77,5 +77,6 @@ extern void Reader_tests(void);
 extern void ReaderNull_tests(void);
 extern void Writer_tests(void);
 extern void WriterGKC_tests(void);
+extern void ReaderWriter_tests(void);
 
 #endif /* Tests_h */