diff --git a/ChangeLog b/ChangeLog
index 5ee1648..1f645cb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,7 @@ Version 4.2.0
  * Replaced 'off_t' parameters and return values with 'int64_t' in
    recently added API functions.
  * Fixed potential uninitialised memory error when closing a wandio writer.
+ * Export symbols for all format-specific open functions.
 
 Version 4.1.2
 =============
diff --git a/debian/changelog b/debian/changelog
index b28c12d..67f5cb7 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -5,6 +5,7 @@ libwandio1 (4.2.0-1) unstable; urgency=medium
   * Replaced 'off_t' parameters and return values with 'int64_t' in
     recently added API functions.
   * Fixed potential uninitialised memory error when closing a wandio writer.
+  * Export symbols for all format-specific 'open' functions.
 
  -- Shane Alcock <salcock@waikato.ac.nz>  Fri, 10 May 2019 13:31:49 +1200
 
diff --git a/lib/ior-bzip.c b/lib/ior-bzip.c
index e935826..5afabf2 100644
--- a/lib/ior-bzip.c
+++ b/lib/ior-bzip.c
@@ -51,7 +51,7 @@ extern io_source_t bz_source;
 #define DATA(io) ((struct bz_t *)((io)->data))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-io_t *bz_open(io_t *parent) {
+DLLEXPORT io_t *bz_open(io_t *parent) {
         io_t *io;
         if (!parent)
                 return NULL;
diff --git a/lib/ior-http.c b/lib/ior-http.c
index 863a83a..e88a1b6 100644
--- a/lib/ior-http.c
+++ b/lib/ior-http.c
@@ -240,7 +240,8 @@ static int fill_buffer(io_t *io) {
         return DATA(io)->l_buf;
 }
 
-io_t *http_open_hdrs(const char *filename, char **hdrs, int hdrs_cnt) {
+DLLEXPORT io_t *http_open_hdrs(const char *filename, char **hdrs, int hdrs_cnt)
+{
         io_t *io = malloc(sizeof(io_t));
         if (!io)
                 return NULL;
@@ -270,7 +271,7 @@ io_t *http_open_hdrs(const char *filename, char **hdrs, int hdrs_cnt) {
         return io;
 }
 
-io_t *http_open(const char *filename) {
+DLLEXPORT io_t *http_open(const char *filename) {
         return http_open_hdrs(filename, NULL, 0);
 }
 
diff --git a/lib/ior-lzma.c b/lib/ior-lzma.c
index edf6a98..b53c98d 100644
--- a/lib/ior-lzma.c
+++ b/lib/ior-lzma.c
@@ -51,7 +51,7 @@ extern io_source_t lzma_source;
 #define DATA(io) ((struct lzma_t *)((io)->data))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-io_t *lzma_open(io_t *parent) {
+DLLEXPORT io_t *lzma_open(io_t *parent) {
         io_t *io;
         if (!parent)
                 return NULL;
diff --git a/lib/ior-peek.c b/lib/ior-peek.c
index 1477cf0..812a0b4 100644
--- a/lib/ior-peek.c
+++ b/lib/ior-peek.c
@@ -65,7 +65,7 @@ extern io_source_t peek_source;
 #define DATA(io) ((struct peek_t *)((io)->data))
 #define MIN(a, b) ((a) < (b) ? (a) : (b))
 
-io_t *peek_open(io_t *child) {
+DLLEXPORT io_t *peek_open(io_t *child) {
         io_t *io;
         if (!child)
                 return NULL;
diff --git a/lib/ior-qat.c b/lib/ior-qat.c
index 74433bf..d703898 100644
--- a/lib/ior-qat.c
+++ b/lib/ior-qat.c
@@ -80,7 +80,7 @@ struct qat_t {
         enum err_t err;
 };
 
-io_t *qat_open(io_t *parent) {
+DLLEXPORT io_t *qat_open(io_t *parent) {
 
         int x;
         io_t *io;
diff --git a/lib/ior-stdio.c b/lib/ior-stdio.c
index 2b507b0..b38d049 100644
--- a/lib/ior-stdio.c
+++ b/lib/ior-stdio.c
@@ -46,7 +46,7 @@ extern io_source_t stdio_source;
 
 #define DATA(io) ((struct stdio_t *)((io)->data))
 
-io_t *stdio_open(const char *filename) {
+DLLEXPORT io_t *stdio_open(const char *filename) {
         io_t *io = malloc(sizeof(io_t));
         io->data = malloc(sizeof(struct stdio_t));
 
diff --git a/lib/ior-swift.c b/lib/ior-swift.c
index 86cff70..727af4b 100644
--- a/lib/ior-swift.c
+++ b/lib/ior-swift.c
@@ -65,7 +65,7 @@ extern io_source_t swift_source;
 #define SWIFT_PFX_LEN 8
 #define SWIFT_AUTH_TOKEN_HDR "X-Auth-Token: "
 
-io_t *swift_open(const char *filename);
+DLLEXPORT io_t *swift_open(const char *filename);
 static int64_t swift_read(io_t *io, void *buffer, int64_t len);
 static int64_t swift_tell(io_t *io);
 static int64_t swift_seek(io_t *io, int64_t offset, int whence);
diff --git a/lib/ior-thread.c b/lib/ior-thread.c
index 0ad2cdf..a9710fa 100644
--- a/lib/ior-thread.c
+++ b/lib/ior-thread.c
@@ -152,7 +152,7 @@ static void *thread_producer(void *userdata) {
         return NULL;
 }
 
-io_t *thread_open(io_t *parent) {
+DLLEXPORT io_t *thread_open(io_t *parent) {
         io_t *state;
         sigset_t set;
         int s;
diff --git a/lib/ior-zlib.c b/lib/ior-zlib.c
index d1fdb14..cc23406 100644
--- a/lib/ior-zlib.c
+++ b/lib/ior-zlib.c
@@ -53,7 +53,7 @@ extern io_source_t zlib_source;
 #define DATA(io) ((struct zlib_t *)((io)->data))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-io_t *zlib_open(io_t *parent) {
+DLLEXPORT io_t *zlib_open(io_t *parent) {
         io_t *io;
         if (!parent)
                 return NULL;
diff --git a/lib/ior-zstd-lz4.c b/lib/ior-zstd-lz4.c
index a83a809..629e1eb 100644
--- a/lib/ior-zstd-lz4.c
+++ b/lib/ior-zstd-lz4.c
@@ -64,7 +64,7 @@ struct zstd_lz4_t {
 #define DATA(io) ((struct zstd_lz4_t *)((io)->data))
 extern io_source_t zstd_lz4_source;
 
-io_t *zstd_lz4_open(io_t *parent) {
+DLLEXPORT io_t *zstd_lz4_open(io_t *parent) {
         io_t *io;
         if (!parent) {
                 return NULL;
diff --git a/lib/iow-bzip.c b/lib/iow-bzip.c
index ff70162..b9ec543 100644
--- a/lib/iow-bzip.c
+++ b/lib/iow-bzip.c
@@ -50,7 +50,7 @@ extern iow_source_t bz_wsource;
 #define DATA(iow) ((struct bzw_t *)((iow)->data))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-iow_t *bz_wopen(iow_t *child, int compress_level) {
+DLLEXPORT iow_t *bz_wopen(iow_t *child, int compress_level) {
         iow_t *iow;
         if (!child)
                 return NULL;
diff --git a/lib/iow-lz4.c b/lib/iow-lz4.c
index 6578f1c..3648942 100644
--- a/lib/iow-lz4.c
+++ b/lib/iow-lz4.c
@@ -54,7 +54,7 @@ struct lz4w_t {
 #define DATA(iow) ((struct lz4w_t *)((iow)->data))
 extern iow_source_t lz4_wsource;
 
-iow_t *lz4_wopen(iow_t *child, int compress_level) {
+DLLEXPORT iow_t *lz4_wopen(iow_t *child, int compress_level) {
         iow_t *iow;
         if (!child) {
                 return NULL;
diff --git a/lib/iow-lzma.c b/lib/iow-lzma.c
index 35979a6..1c93afd 100644
--- a/lib/iow-lzma.c
+++ b/lib/iow-lzma.c
@@ -51,7 +51,7 @@ extern iow_source_t lzma_wsource;
 #define DATA(iow) ((struct lzmaw_t *)((iow)->data))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-iow_t *lzma_wopen(iow_t *child, int compress_level) {
+DLLEXPORT iow_t *lzma_wopen(iow_t *child, int compress_level) {
         iow_t *iow;
         if (!child)
                 return NULL;
diff --git a/lib/iow-lzo.c b/lib/iow-lzo.c
index 54110b4..9db05c0 100644
--- a/lib/iow-lzo.c
+++ b/lib/iow-lzo.c
@@ -265,7 +265,7 @@ static void *lzo_compress_thread(void *data) {
         return NULL;
 }
 
-iow_t *lzo_wopen(iow_t *child, int compress_level) {
+DLLEXPORT iow_t *lzo_wopen(iow_t *child, int compress_level) {
         const int opt_filter = 0;
         int flags;
         iow_t *iow;
diff --git a/lib/iow-qat.c b/lib/iow-qat.c
index 798b393..a2110aa 100644
--- a/lib/iow-qat.c
+++ b/lib/iow-qat.c
@@ -79,7 +79,7 @@ static void qat_perror(int errcode) {
         }
 }
 
-iow_t *qat_wopen(iow_t *child, int compress_level) {
+DLLEXPORT iow_t *qat_wopen(iow_t *child, int compress_level) {
 
         iow_t *iow;
         QzSessionParams_T params;
diff --git a/lib/iow-stdio.c b/lib/iow-stdio.c
index 934a224..2858943 100644
--- a/lib/iow-stdio.c
+++ b/lib/iow-stdio.c
@@ -96,7 +96,7 @@ static int safe_open(const char *filename, int flags) {
         return fd;
 }
 
-iow_t *stdio_wopen(const char *filename, int flags) {
+DLLEXPORT iow_t *stdio_wopen(const char *filename, int flags) {
         iow_t *iow = malloc(sizeof(iow_t));
         iow->source = &stdio_wsource;
         iow->data = malloc(sizeof(struct stdiow_t));
diff --git a/lib/iow-thread.c b/lib/iow-thread.c
index d045331..a409bb6 100644
--- a/lib/iow-thread.c
+++ b/lib/iow-thread.c
@@ -150,7 +150,7 @@ static void *thread_consumer(void *userdata) {
         return NULL;
 }
 
-iow_t *thread_wopen(iow_t *child) {
+DLLEXPORT iow_t *thread_wopen(iow_t *child) {
         iow_t *state;
 
         if (!child) {
diff --git a/lib/iow-zlib.c b/lib/iow-zlib.c
index 50bca06..3c7e0d6 100644
--- a/lib/iow-zlib.c
+++ b/lib/iow-zlib.c
@@ -51,7 +51,7 @@ extern iow_source_t zlib_wsource;
 #define DATA(iow) ((struct zlibw_t *)((iow)->data))
 #define min(a, b) ((a) < (b) ? (a) : (b))
 
-iow_t *zlib_wopen(iow_t *child, int compress_level) {
+DLLEXPORT iow_t *zlib_wopen(iow_t *child, int compress_level) {
         iow_t *iow;
         if (!child)
                 return NULL;
diff --git a/lib/iow-zstd.c b/lib/iow-zstd.c
index 6586cb7..45680fb 100644
--- a/lib/iow-zstd.c
+++ b/lib/iow-zstd.c
@@ -46,7 +46,7 @@ struct zstdw_t {
 #define DATA(iow) ((struct zstdw_t *)((iow)->data))
 extern iow_source_t zstd_wsource;
 
-iow_t *zstd_wopen(iow_t *child, int compress_level) {
+DLLEXPORT iow_t *zstd_wopen(iow_t *child, int compress_level) {
         iow_t *iow;
         if (!child)
                 return NULL;