diff --git a/src/support/docstring.cpp b/src/support/docstring.cpp
index 30298b5f59..d19c2e39be 100644
--- a/src/support/docstring.cpp
+++ b/src/support/docstring.cpp
@@ -25,6 +25,7 @@
 
 using namespace std;
 
+using lyx::support::isHexChar;
 
 namespace lyx {
 
diff --git a/src/support/lstrings.cpp b/src/support/lstrings.cpp
index 4ba72d8081..18e6947ae4 100644
--- a/src/support/lstrings.cpp
+++ b/src/support/lstrings.cpp
@@ -332,7 +332,7 @@ bool hasDigitASCII(docstring const & str)
 }
 
 
-static bool isHexChar(char_type c)
+bool isHexChar(char_type c)
 {
 	return c == '0' ||
 		c == '1' ||
diff --git a/src/support/lstrings.h b/src/support/lstrings.h
index 46e4e814b2..d0f7480365 100644
--- a/src/support/lstrings.h
+++ b/src/support/lstrings.h
@@ -47,6 +47,8 @@ bool isStrDbl(std::string const & str);
 /// does the string contain a digit?
 bool hasDigitASCII(docstring const & str);
 
+bool isHexChar(char_type);
+
 bool isHex(docstring const & str);
 
 int hexToInt(docstring const & str);