diff --git a/src/tree_schema_internal.h b/src/tree_schema_internal.h
index 59e7d29..abec951 100644
--- a/src/tree_schema_internal.h
+++ b/src/tree_schema_internal.h
@@ -22,6 +22,8 @@
 #include "tree_schema.h"
 #include "xml.h"
 
+#define YIN_NS_URI "urn:ietf:params:xml:ns:yang:yin:1"
+
 #define LOGVAL_PARSER(CTX, ...) LOGVAL((CTX)->ctx, (CTX)->pos_type, (CTX)->pos_type == LY_VLOG_LINE ? &(CTX)->line : (void*)(CTX)->path, __VA_ARGS__)
 
 /**