diff --git a/README.rst b/README.rst
index 4ea8977..fc7798f 100644
--- a/README.rst
+++ b/README.rst
@@ -43,11 +43,14 @@ On a Debian/Ubuntu system::
 Compatibility
 -------------
 
-The current version requires at least C `libyang 2.25`__.
+The current version requires at least C `libyang 4.0`__ (devel branch).
+
+For C `libyang 3.x`__, use an earlier version of these bindings.
 
 The last version of the bindings that works with C `libyang 1.x`__ is v1.7.0__.
 
-__ https://github.com/CESNET/libyang/commit/d2f1608b348f
+__ https://github.com/CESNET/libyang/tree/devel
+__ https://github.com/CESNET/libyang/tree/master
 __ https://github.com/CESNET/libyang/tree/libyang1
 __ https://pypi.org/project/libyang/1.7.0/
 
diff --git a/_codeql_detected_source_root b/_codeql_detected_source_root
new file mode 120000
index 0000000..945c9b4
--- /dev/null
+++ b/_codeql_detected_source_root
@@ -0,0 +1 @@
+.
\ No newline at end of file
diff --git a/cffi/cdefs.h b/cffi/cdefs.h
index 52f00b2..8e95225 100644
--- a/cffi/cdefs.h
+++ b/cffi/cdefs.h
@@ -36,7 +36,7 @@ typedef enum {
     LY_EPLUGIN = 128
 } LY_ERR;
 
-LY_ERR ly_ctx_new(const char *, uint16_t, struct ly_ctx **);
+LY_ERR ly_ctx_new(const char *, uint32_t, struct ly_ctx **);
 void ly_ctx_destroy(struct ly_ctx *);
 int ly_ctx_set_searchdir(struct ly_ctx *, const char *);
 
@@ -350,7 +350,7 @@ LY_ERR ly_out_new_file(FILE *, struct ly_out **);
 LY_ERR ly_out_new_fd(int, struct ly_out **);
 
 LY_ERR lyd_parse_data(const struct ly_ctx *, struct lyd_node *, struct ly_in *, LYD_FORMAT, uint32_t, uint32_t, struct lyd_node **);
-LY_ERR lyd_parse_op(const struct ly_ctx *, struct lyd_node *, struct ly_in *, LYD_FORMAT, enum lyd_type, struct lyd_node **, struct lyd_node **);
+LY_ERR lyd_parse_op(const struct ly_ctx *, struct lyd_node *, struct ly_in *, LYD_FORMAT, enum lyd_type, uint32_t, struct lyd_node **, struct lyd_node **);
 
 typedef enum {
    LYS_OUT_UNKNOWN,
@@ -392,7 +392,6 @@ struct lys_module {
     struct lys_module **deviated_by;
     ly_bool implemented;
     ly_bool to_compile;
-    uint8_t latest_revision;
     ...;
 };
 
@@ -466,12 +465,11 @@ struct lysp_ext_instance {
     const char *argument;
     LY_VALUE_FORMAT format;
     void *prefix_data;
-    struct lysp_ext *def;
+    uintptr_t plugin_ref;
     void *parent;
     enum ly_stmt parent_stmt;
     uint64_t parent_stmt_index;
     uint16_t flags;
-    const struct lyplg_ext_record *record;
     struct lysp_ext_substmt *substmts;
     void *parsed;
     struct lysp_stmt *child;
@@ -609,6 +607,13 @@ struct lysp_node_container {
     ...;
 };
 
+struct lysc_prefix;
+
+struct lysc_value {
+    const char *str;
+    struct lysc_prefix *prefixes;
+};
+
 struct lysc_node_leaf {
     union {
         struct lysc_node node;
@@ -622,7 +627,7 @@ struct lysc_node_leaf {
     struct lysc_when **when;
     struct lysc_type *type;
     const char *units;
-    struct lyd_value *dflt;
+    struct lysc_value dflt;
     ...;
 };
 
@@ -652,7 +657,7 @@ struct lysc_node_leaflist {
     struct lysc_when **when;
     struct lysc_type *type;
     const char *units;
-    struct lyd_value **dflts;
+    struct lysc_value *dflts;
     uint32_t min;
     uint32_t max;
     ...;
@@ -782,7 +787,7 @@ struct lysp_node_augment {
 struct lysc_type {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
 };
@@ -858,7 +863,7 @@ struct lysc_ext {
     const char *name;
     const char *argname;
     struct lysc_ext_instance *exts;
-    struct lyplg_ext *plugin;
+    uintptr_t plugin_ref;
     struct lys_module *module;
     uint16_t flags;
 };
@@ -981,7 +986,6 @@ typedef struct pcre2_real_code pcre2_code;
 
 struct lysc_pattern {
     const char *expr;
-    pcre2_code *code;
     const char *dsc;
     const char *ref;
     const char *emsg;
@@ -1016,7 +1020,7 @@ struct lysc_ident {
 struct lysc_type_num {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lysc_range *range;
@@ -1025,7 +1029,7 @@ struct lysc_type_num {
 struct lysc_type_dec {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     uint8_t fraction_digits;
@@ -1035,7 +1039,7 @@ struct lysc_type_dec {
 struct lysc_type_str {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lysc_range *length;
@@ -1057,7 +1061,7 @@ struct lysc_type_bitenum_item {
 struct lysc_type_enum {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lysc_type_bitenum_item *enums;
@@ -1066,7 +1070,7 @@ struct lysc_type_enum {
 struct lysc_type_bits {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lysc_type_bitenum_item *bits;
@@ -1075,7 +1079,7 @@ struct lysc_type_bits {
 struct lysc_type_leafref {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lyxp_expr *path;
@@ -1087,7 +1091,7 @@ struct lysc_type_leafref {
 struct lysc_type_identityref {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lysc_ident **bases;
@@ -1096,7 +1100,7 @@ struct lysc_type_identityref {
 struct lysc_type_instanceid {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     uint8_t require_instance;
@@ -1105,7 +1109,7 @@ struct lysc_type_instanceid {
 struct lysc_type_union {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lysc_type **types;
@@ -1114,7 +1118,7 @@ struct lysc_type_union {
 struct lysc_type_bin {
     const char *name;
     struct lysc_ext_instance *exts;
-    struct lyplg_type *plugin;
+    uintptr_t plugin_ref;
     LY_DATA_TYPE basetype;
     uint32_t refcount;
     struct lysc_range *length;
@@ -1158,8 +1162,7 @@ typedef enum {
    LYD_ANYDATA_DATATREE,
    LYD_ANYDATA_STRING,
    LYD_ANYDATA_XML,
-   LYD_ANYDATA_JSON,
-   LYD_ANYDATA_LYB
+   LYD_ANYDATA_JSON
 } LYD_ANYDATA_VALUETYPE;
 
 union lyd_any_value {
@@ -1167,7 +1170,6 @@ union lyd_any_value {
     const char *str;
     const char *xml;
     const char *json;
-    char *mem;
 };
 
 struct lyd_node_any {
@@ -1333,7 +1335,7 @@ struct ly_ctx *lyplg_ext_compile_get_ctx(const struct lysc_ctx *);
 void lyplg_ext_parse_log(const struct lysp_ctx *, const struct lysp_ext_instance *, LY_LOG_LEVEL, LY_ERR, const char *, ...);
 void lyplg_ext_compile_log(const struct lysc_ctx *, const struct lysc_ext_instance *, LY_LOG_LEVEL, LY_ERR, const char *, ...);
 LY_ERR lyplg_ext_parse_extension_instance(struct lysp_ctx *, struct lysp_ext_instance *);
-LY_ERR lyplg_ext_compile_extension_instance(struct lysc_ctx *, const struct lysp_ext_instance *, struct lysc_ext_instance *);
+LY_ERR lyplg_ext_compile_extension_instance(struct lysc_ctx *, const struct lysp_ext_instance *, struct lysc_ext_instance *, struct lysc_node *);
 void lyplg_ext_pfree_instance_substatements(const struct ly_ctx *ctx, struct lysp_ext_substmt *substmts);
 void lyplg_ext_cfree_instance_substatements(const struct ly_ctx *ctx, struct lysc_ext_substmt *substmts);
 typedef LY_ERR (*lyplg_ext_parse_clb)(struct lysp_ctx *, struct lysp_ext_instance *);
diff --git a/cffi/source.c b/cffi/source.c
index 34e18b0..beb7f76 100644
--- a/cffi/source.c
+++ b/cffi/source.c
@@ -6,6 +6,6 @@
 #include <libyang/libyang.h>
 #include <libyang/version.h>
 
-#if LY_VERSION_MAJOR * 10000 + LY_VERSION_MINOR * 100 + LY_VERSION_MICRO < 30801
-#error "This version of libyang bindings only works with libyang soversion 3.8.1+"
+#if LY_VERSION_MAJOR * 10000 + LY_VERSION_MINOR * 100 + LY_VERSION_MICRO < 40000
+#error "This version of libyang bindings only works with libyang soversion 4.0.0+"
 #endif
diff --git a/libyang/extension.py b/libyang/extension.py
index 57f7cb2..2ff3f22 100644
--- a/libyang/extension.py
+++ b/libyang/extension.py
@@ -25,7 +25,7 @@ def __init__(self, message: str, ret: int, log_level: int) -> None:
 
 @ffi.def_extern(name="lypy_lyplg_ext_parse_clb")
 def libyang_c_lyplg_ext_parse_clb(pctx, pext):
-    plugin = extensions_plugins[pext.record.plugin]
+    plugin = extensions_plugins[pext.plugin_ref]
     module_cdata = lib.lyplg_ext_parse_get_cur_pmod(pctx).mod
     context = Context(cdata=module_cdata.ctx)
     module = Module(context, module_cdata)
@@ -46,7 +46,7 @@ def libyang_c_lyplg_ext_parse_clb(pctx, pext):
 
 @ffi.def_extern(name="lypy_lyplg_ext_compile_clb")
 def libyang_c_lyplg_ext_compile_clb(cctx, pext, cext):
-    plugin = extensions_plugins[pext.record.plugin]
+    plugin = extensions_plugins[pext.plugin_ref]
     context = Context(cdata=lib.lyplg_ext_compile_get_ctx(cctx))
     module = Module(context, cext.module)
     parsed_ext = ExtensionParsed(context, pext, module)
@@ -67,7 +67,7 @@ def libyang_c_lyplg_ext_compile_clb(cctx, pext, cext):
 
 @ffi.def_extern(name="lypy_lyplg_ext_parse_free_clb")
 def libyang_c_lyplg_ext_parse_free_clb(ctx, pext):
-    plugin = extensions_plugins[pext.record.plugin]
+    plugin = extensions_plugins[pext.plugin_ref]
     context = Context(cdata=ctx)
     parsed_ext = ExtensionParsed(context, pext, None)
     plugin.parse_free_clb(parsed_ext)
@@ -75,7 +75,7 @@ def libyang_c_lyplg_ext_parse_free_clb(ctx, pext):
 
 @ffi.def_extern(name="lypy_lyplg_ext_compile_free_clb")
 def libyang_c_lyplg_ext_compile_free_clb(ctx, cext):
-    plugin = extensions_plugins[getattr(cext, "def").plugin]
+    plugin = extensions_plugins[getattr(cext, "def").plugin_ref]
     context = Context(cdata=ctx)
     compiled_ext = ExtensionCompiled(context, cext)
     plugin.compile_free_clb(compiled_ext)