diff --git a/json.h b/json.h
index fc2dadd..76d1f0f 100644
--- a/json.h
+++ b/json.h
@@ -35,4 +35,8 @@ extern "C" {
 }
 #endif
 
+#ifdef TEST
+#include "test_common.h"
+#endif
+
 #endif
diff --git a/tests/Makefile.am b/tests/Makefile.am
index ea57bda..8c17473 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,5 +1,5 @@
 
-AM_CPPFLAGS = -I$(top_srcdir) -I$(top_srcdir)/tests
+AM_CPPFLAGS = -I$(top_srcdir) -I$(top_srcdir)/tests -DTEST
 
 LDADD= $(LIBJSON_LA)
 
diff --git a/tests/test_common.h b/tests/test_common.h
new file mode 100644
index 0000000..516cd05
--- /dev/null
+++ b/tests/test_common.h
@@ -0,0 +1,4 @@
+
+#ifdef NDEBUG
+#undef NDEBUG
+#endif