diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 3b4c181e5..baff6624c 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -45,6 +45,10 @@
 extern char * * environ __attribute__((weak));
 
 
+#ifdef NDEBUG
+#error "Nix may not be built with assertions disabled (i.e. with -DNDEBUG)."
+#endif
+
 namespace nix {
 
 void initLibUtil() {
diff --git a/tests/unit/libstore/outputs-spec.cc b/tests/unit/libstore/outputs-spec.cc
index 456196be1..63cde681b 100644
--- a/tests/unit/libstore/outputs-spec.cc
+++ b/tests/unit/libstore/outputs-spec.cc
@@ -6,11 +6,9 @@
 
 namespace nix {
 
-#ifndef NDEBUG
 TEST(OutputsSpec, no_empty_names) {
     ASSERT_DEATH(OutputsSpec::Names { std::set<std::string> { } }, "");
 }
-#endif
 
 #define TEST_DONT_PARSE(NAME, STR)           \
     TEST(OutputsSpec, bad_ ## NAME) {        \