diff --git a/src/libutil-test-support/tests/gtest-with-params.hh b/src/libutil-test-support/tests/gtest-with-params.hh
index d72aec4fd..a6e23ad89 100644
--- a/src/libutil-test-support/tests/gtest-with-params.hh
+++ b/src/libutil-test-support/tests/gtest-with-params.hh
@@ -40,7 +40,7 @@ void checkGTestWith(Testable && testable, MakeTestParams makeTestParams)
     } else {
         std::ostringstream ss;
         printResultMessage(result, ss);
-        FAIL() << ss.str() << std::endl;
+        throw std::runtime_error(ss.str());
     }
 }
 }
diff --git a/src/libutil-test-support/tests/nix_api_util.hh b/src/libutil-test-support/tests/nix_api_util.hh
index efd200116..006dc497c 100644
--- a/src/libutil-test-support/tests/nix_api_util.hh
+++ b/src/libutil-test-support/tests/nix_api_util.hh
@@ -26,14 +26,13 @@ protected:
 
     inline void assert_ctx_ok()
     {
-
         if (nix_err_code(ctx) == NIX_OK) {
             return;
         }
         unsigned int n;
         const char * p = nix_err_msg(nullptr, ctx, &n);
         std::string msg(p, n);
-        FAIL() << "nix_err_code(ctx) != NIX_OK, message: " << msg;
+        throw std::runtime_error(std::string("nix_err_code(ctx) != NIX_OK, message: ") + msg);
     }
 
     inline void assert_ctx_err()
@@ -41,7 +40,7 @@ protected:
         if (nix_err_code(ctx) != NIX_OK) {
             return;
         }
-        FAIL() << "Got NIX_OK, but expected an error!";
+        throw std::runtime_error("Got NIX_OK, but expected an error!");
     }
 };