diff --git a/src/HTMLRenderer/install.cc b/src/HTMLRenderer/install.cc
index a01fa8b..039e60a 100644
--- a/src/HTMLRenderer/install.cc
+++ b/src/HTMLRenderer/install.cc
@@ -19,6 +19,8 @@
 #include "namespace.h"
 #include "util.h"
 
+using std::abs;
+
 FontInfo HTMLRenderer::install_font(GfxFont * font)
 {
     assert(sizeof(long long) == 2*sizeof(int));
diff --git a/src/HTMLRenderer/state.cc b/src/HTMLRenderer/state.cc
index 4c04fab..2342775 100644
--- a/src/HTMLRenderer/state.cc
+++ b/src/HTMLRenderer/state.cc
@@ -18,6 +18,7 @@
 #include "namespace.h"
 
 using std::max;
+using std::abs;
 
 void HTMLRenderer::updateAll(GfxState * state) 
 {