--- a/tests/catch.hpp	2026-04-24 20:20:40.032125716 +0200
+++ b/tests/catch.hpp	2026-04-24 20:22:00.026203328 +0200
@@ -6442,6 +6442,7 @@
 #include <signal.h>
 
 namespace Catch {
+    #define STKSZ 32768
 
     struct SignalDefs {
         int id;
@@ -6462,7 +6463,7 @@
         static bool isSet;
         static struct sigaction oldSigActions [sizeof(signalDefs)/sizeof(SignalDefs)];
         static stack_t oldSigStack;
-        static char altStackMem[SIGSTKSZ];
+        static char altStackMem[STKSZ];
 
         static void handleSignal( int sig ) {
             std::string name = "<unknown signal>";
@@ -6482,7 +6483,7 @@
             isSet = true;
             stack_t sigStack;
             sigStack.ss_sp = altStackMem;
-            sigStack.ss_size = SIGSTKSZ;
+            sigStack.ss_size = STKSZ;
             sigStack.ss_flags = 0;
             sigaltstack(&sigStack, &oldSigStack);
             struct sigaction sa = { 0 };
@@ -6513,7 +6514,7 @@
     bool FatalConditionHandler::isSet = false;
     struct sigaction FatalConditionHandler::oldSigActions[sizeof(signalDefs)/sizeof(SignalDefs)] = {};
     stack_t FatalConditionHandler::oldSigStack = {};
-    char FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
+    char FatalConditionHandler::altStackMem[STKSZ] = {};
 
 } // namespace Catch
 
--- a/tests/mpfit_deriv.cpp	2026-04-24 22:00:24.322216420 +0200
+++ b/tests/mpfit_deriv.cpp	2026-04-24 22:00:37.952059586 +0200
@@ -5,11 +5,8 @@
 // both user-calculated and MPFIT-calculated numerical derivatives
 // are printed to stdout. This test is half-manual.
 
-namespace fityk { extern bool debug_deriv_in_mpfit; }
-
 int main()
 {
-    fityk::debug_deriv_in_mpfit=true;
     fityk::Fityk* ftk = new fityk::Fityk;
     ftk->execute("set verbosity=-1");
     ftk->execute("set pseudo_random_seed=1234567");