diff --git a/swig/libpwrnlperror.i b/swig/libpwrnlperror.i
index 9a401588b66c2e3e9bb9ad5ede5d655ece8e2eb5..31b715783ae28e70593b616c22dae756dc55e083 100644
--- a/swig/libpwrnlperror.i
+++ b/swig/libpwrnlperror.i
@@ -6,6 +6,7 @@
   #include <libpwrutils/exception.h>
 %} 
 
+%include "std_string.i"
 %include "std_except.i"
 
 %nodefaultctor PwrNlp::PwrNlpError;