diff --git a/src/cosserat-continuum.cc b/src/cosserat-continuum.cc
index f58b44964a1c18e659adec1709a0f04c14a2db5f..6a3f01713f7fa4d9fc9ef3d495d7e7738e53d885 100644
--- a/src/cosserat-continuum.cc
+++ b/src/cosserat-continuum.cc
@@ -4,6 +4,9 @@
 
 #include <fenv.h>
 
+// Hack to make IPOpt happy.  No idea why the build system doesn't properly handle this
+#define HAVE_CSTDDEF
+
 // Includes for the ADOL-C automatic differentiation library
 // Need to come before (almost) all others.
 #include <adolc/adouble.h>
diff --git a/src/finite-strain-elasticity.cc b/src/finite-strain-elasticity.cc
index 512449410f1a9a1a83b0883545f953ce40806838..2ae6c03b807dbfc31a068cde26c576e1f56e55e0 100644
--- a/src/finite-strain-elasticity.cc
+++ b/src/finite-strain-elasticity.cc
@@ -1,5 +1,8 @@
 #include <config.h>
 
+// Hack to make IPOpt happy.  No idea why the build system doesn't properly handle this
+#define HAVE_CSTDDEF
+
 // Includes for the ADOL-C automatic differentiation library
 // Need to come before (almost) all others.
 #include <adolc/adouble.h>