1 files changed, 6 insertions, 1 deletions
diff --git a/libtests/matrix.cc b/libtests/matrix.cc
index ecaa02a0..210c022f 100644
--- a/libtests/matrix.cc
+++ b/libtests/matrix.cc
@@ -1,8 +1,13 @@
 #include <qpdf/QPDFMatrix.hh>
 #include <qpdf/QUtil.hh>
-#include <assert.h>
 #include <iostream>
 
+#ifdef NDEBUG
+// We need assert even in a release build for test code.
+# undef NDEBUG
+#endif
+#include <cassert>
+
 static void check(QPDFMatrix const& m, std::string const& exp)
 {
     std::string u = m.unparse();