diff --git a/chapters/functions.tex b/chapters/functions.tex
index 0cb2bdc9a..a510e645d 100644
--- a/chapters/functions.tex
+++ b/chapters/functions.tex
@@ -2047,6 +2047,7 @@ \subsubsection{Simple Types}\label{simple-types}
 \end{center}
 
 Sending string literals to FORTRAN~77 subroutines/functions is supported for Lapack/Blas-routines, and the strings are \textsc{nul}-terminated for compatibility with C.
+The strings should be UTF-8 encoded similarly as for C to be compatible with C, even though the support in FORTRAN~77 is unclear and it is not relevant for the Lapack/Blas-routines.
 Returning strings from FORTRAN~77 subroutines/functions is currently not supported.
 
 Enumeration types used as arguments are mapped to type int when calling an external C function, and to type \lstinline!INTEGER! when calling an external FORTRAN function.