diff --git a/dcalc/FindRoot.cc b/dcalc/FindRoot.cc
index ad96796c..a6bdde60 100644
--- a/dcalc/FindRoot.cc
+++ b/dcalc/FindRoot.cc
@@ -16,8 +16,12 @@
 
 #include "FindRoot.hh"
 
+#include <algorithm> // abs
+
 namespace sta {
 
+using std::abs;
+
 double
 findRoot(FindRootFunc func,
 	 double x1,
diff --git a/dcalc/FindRoot.hh b/dcalc/FindRoot.hh
index 2bc9a8eb..1a62df8b 100644
--- a/dcalc/FindRoot.hh
+++ b/dcalc/FindRoot.hh
@@ -16,7 +16,7 @@
 
 #pragma once
 
-#include <algorithm> // abs, min
+#include <functional>
 
 namespace sta {