diff --git a/src/schema_compile_node.c b/src/schema_compile_node.c
index 0e08923..3776da9 100644
--- a/src/schema_compile_node.c
+++ b/src/schema_compile_node.c
@@ -1176,6 +1176,7 @@
     const char *orig_ptr;
     PCRE2_SIZE err_offset;
     pcre2_code *code_local;
+    ly_bool escaped;
     LY_ERR r;
 
     /* adjust the expression to a Perl equivalent
@@ -1197,6 +1198,7 @@
     /* we need to replace all "$" and "^" (that are not in "[]") with "\$" and "\^" */
     brack = 0;
     idx = 0;
+    escaped = 0;
     orig_ptr = pattern;
     while (orig_ptr[0]) {
         switch (orig_ptr[0]) {
@@ -1213,16 +1215,30 @@
                 ++idx;
             }
             break;
+        case '\\':
+            /*  escape character found or backslash is escaped */
+            escaped = !escaped;
+            /* copy backslash and continue with the next character */
+            perl_regex[idx] = orig_ptr[0];
+            ++idx;
+            ++orig_ptr;
+            continue;
         case '[':
-            /* must not be escaped */
-            if ((orig_ptr == pattern) || (orig_ptr[-1] != '\\')) {
+            if (!escaped) {
                 ++brack;
             }
             break;
         case ']':
-            if ((orig_ptr == pattern) || (orig_ptr[-1] != '\\')) {
-                /* pattern was checked and compiled already */
-                assert(brack);
+            if (!brack && !escaped) {
+                /* If ']' does not terminate a character class expression, then pcre2_compile() implicitly escapes the
+                 * ']' character. But this seems to be against the regular expressions rules declared in
+                 * "XML schema: Datatypes" and therefore an error is returned. So for example if pattern is '\[a]' then
+                 * pcre2 match characters '[a]' literally but in YANG such pattern is not allowed.
+                 */
+                LOGVAL(ctx, LY_VCODE_INREGEXP, pattern, orig_ptr, "character group doesn't begin with '['");
+                free(perl_regex);
+                return LY_EVALID;
+            } else if (!escaped) {
                 --brack;
             }
             break;
@@ -1235,6 +1251,7 @@
 
         ++idx;
         ++orig_ptr;
+        escaped = 0;
     }
 #ifndef PCRE2_ENDANCHORED
     /* anchor match to end of subject */
diff --git a/tests/utests/types/string.c b/tests/utests/types/string.c
index 466c1ae..47ad0ad 100644
--- a/tests/utests/types/string.c
+++ b/tests/utests/types/string.c
@@ -314,6 +314,24 @@
     CHECK_LYSP_NODE_LEAF(lysp_leaf, NULL, 0, 0x0, 0, "port", 0, 0, NULL, 0, 0, NULL, NULL);
     CHECK_LYSP_TYPE(&(lysp_leaf->type), 0, 0, 0, 0, 0, 0x0, 0, 0, "my_type", 0, 0, 1, 0, 0, 0);
 
+    /* TEST pattern backslash
+     * The '[' character is escaped, thus character group is broken.
+     */
+
+    schema = MODULE_CREATE_YANG("TPATTERN_BC_ERR_1", "leaf port {type string {"
+            "pattern '\\[a]b';" /* pattern '\[a]b'; */
+            "}}");
+    UTEST_INVALID_MODULE(schema, LYS_IN_YANG, NULL, LY_EVALID);
+    CHECK_LOG_CTX("Regular expression \"\\[a]b\" is not valid (\"]b\": character group doesn't begin with '[').",
+            "/TPATTERN_BC_ERR_1:port");
+
+    schema = MODULE_CREATE_YANG("TPATTERN_BC_ERR_2", "leaf port {type string {"
+            "pattern \"\\\\[a]b\";" /* pattern "\\[a]b"; */
+            "}}");
+    UTEST_INVALID_MODULE(schema, LYS_IN_YANG, NULL, LY_EVALID);
+    CHECK_LOG_CTX("Regular expression \"\\[a]b\" is not valid (\"]b\": character group doesn't begin with '[').",
+            "/TPATTERN_BC_ERR_2:port");
+
     /* PATTERN AND LENGTH */
     schema = MODULE_CREATE_YANG("TPL_0",
             "typedef my_type {"
@@ -1139,6 +1157,30 @@
     assert_int_equal(LY_EINVAL, ly_ret);
     ly_err_free(err);
 
+    /* TEST pattern backslash */
+
+    schema = MODULE_CREATE_YANG("TPATTERN_BC_1", "leaf port {type string {"
+            "pattern '\\\\[a]b';"  /* pattern '\\[a]b'; */
+            "}}");
+    UTEST_ADD_MODULE(schema, LYS_IN_YANG, NULL, &mod);
+    lysc_type = ((struct lysc_node_leaf *)mod->compiled->data)->type;
+    val_text = "\\ab";
+    assert_int_equal(LY_SUCCESS, type->store(UTEST_LYCTX, lysc_type, val_text, strlen(val_text),
+            0, LY_VALUE_XML, NULL, LYD_VALHINT_STRING, NULL, &value, NULL, &err));
+    CHECK_LYD_VALUE(value, STRING, "\\ab");
+    type->free(UTEST_LYCTX, &value);
+
+    schema = MODULE_CREATE_YANG("TPATTERN_BC_2", "leaf port {type string {"
+            "pattern \"\\\\\\\\[a]b\";" /* pattern "\\\\[a]b"; */
+            "}}");
+    UTEST_ADD_MODULE(schema, LYS_IN_YANG, NULL, &mod);
+    lysc_type = ((struct lysc_node_leaf *)mod->compiled->data)->type;
+    val_text = "\\ab";
+    assert_int_equal(LY_SUCCESS, type->store(UTEST_LYCTX, lysc_type, val_text, strlen(val_text),
+            0, LY_VALUE_XML, NULL, LYD_VALHINT_STRING, NULL, &value, NULL, &err));
+    CHECK_LYD_VALUE(value, STRING, "\\ab");
+    type->free(UTEST_LYCTX, &value);
+
     /* ERROR TESTS */
 
     val_text = "10 \"| bcdei";