diff --git a/src/mathed/formulabase.C b/src/mathed/formulabase.C
index abbdd0831c..5cb18758c3 100644
--- a/src/mathed/formulabase.C
+++ b/src/mathed/formulabase.C
@@ -55,6 +55,7 @@
 using std::endl;
 using std::ostream;
 using std::vector;
+using std::abs;
 
 MathCursor * mathcursor = 0;