diff --color -ru a/include/internal/catch_fatal_condition.hpp b/include/internal/catch_fatal_condition.hpp
--- a/include/internal/catch_fatal_condition.hpp	2018-05-14 15:15:28.000000000 +0200
+++ b/include/internal/catch_fatal_condition.hpp	2021-07-15 14:08:17.297322549 +0200
@@ -133,10 +133,11 @@
 
     struct FatalConditionHandler {
 
+        static char* altStackMem;
+        static std::size_t altStackSize;
         static bool isSet;
         static struct sigaction oldSigActions [sizeof(signalDefs)/sizeof(SignalDefs)];
         static stack_t oldSigStack;
-        static char altStackMem[SIGSTKSZ];
 
         static void handleSignal( int sig ) {
             std::string name = "<unknown signal>";
@@ -153,10 +154,16 @@
         }
 
         FatalConditionHandler() {
+            assert(!altStackMem && "Cannot initialize POSIX signal handler when one already exists");
+            if (altStackSize == 0) {
+                altStackSize = std::max(static_cast<size_t>(SIGSTKSZ), (size_t)(32 * 1024));
+            }
+            altStackMem = new char[altStackSize]();
+
             isSet = true;
             stack_t sigStack;
             sigStack.ss_sp = altStackMem;
-            sigStack.ss_size = SIGSTKSZ;
+            sigStack.ss_size = altStackSize;
             sigStack.ss_flags = 0;
             sigaltstack(&sigStack, &oldSigStack);
             struct sigaction sa = { 0 };
@@ -171,6 +178,11 @@
 
         ~FatalConditionHandler() {
             reset();
+
+            delete[] altStackMem;
+            // We signal that another instance can be constructed by zeroing
+            // out the pointer.
+            altStackMem = nullptr;
         }
         static void reset() {
             if( isSet ) {
@@ -185,10 +197,11 @@
         }
     };
 
+    char* FatalConditionHandler::altStackMem = nullptr;
+    std::size_t FatalConditionHandler::altStackSize = 0;
     bool FatalConditionHandler::isSet = false;
     struct sigaction FatalConditionHandler::oldSigActions[sizeof(signalDefs)/sizeof(SignalDefs)] = {};
     stack_t FatalConditionHandler::oldSigStack = {};
-    char FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
 
 
 } // namespace Catch
diff --color -ru a/single_include/catch.hpp b/single_include/catch.hpp
--- a/single_include/catch.hpp	2018-05-14 15:15:28.000000000 +0200
+++ b/single_include/catch.hpp	2021-07-15 14:21:18.755941570 +0200
@@ -6537,10 +6537,11 @@
 
     struct FatalConditionHandler {
 
+        static char* altStackMem;
+        static std::size_t altStackSize;
         static bool isSet;
         static struct sigaction oldSigActions [sizeof(signalDefs)/sizeof(SignalDefs)];
         static stack_t oldSigStack;
-        static char altStackMem[SIGSTKSZ];
 
         static void handleSignal( int sig ) {
             std::string name = "<unknown signal>";
@@ -6557,10 +6558,16 @@
         }
 
         FatalConditionHandler() {
+            assert(!altStackMem && "Cannot initialize POSIX signal handler when one already exists");
+            if (altStackSize == 0) {
+                altStackSize = std::max(static_cast<size_t>(SIGSTKSZ), (size_t)(32 * 1024));
+            }
+            altStackMem = new char[altStackSize]();
+
             isSet = true;
             stack_t sigStack;
             sigStack.ss_sp = altStackMem;
-            sigStack.ss_size = SIGSTKSZ;
+            sigStack.ss_size = altStackSize;
             sigStack.ss_flags = 0;
             sigaltstack(&sigStack, &oldSigStack);
             struct sigaction sa = { 0 };
@@ -6574,6 +6581,11 @@
 
         ~FatalConditionHandler() {
             reset();
+
+            delete[] altStackMem;
+            // We signal that another instance can be constructed by zeroing
+            // out the pointer.
+            altStackMem = nullptr;
         }
         static void reset() {
             if( isSet ) {
@@ -6588,10 +6600,11 @@
         }
     };
 
+    char* FatalConditionHandler::altStackMem = nullptr;
+    std::size_t FatalConditionHandler::altStackSize = 0;
     bool FatalConditionHandler::isSet = false;
     struct sigaction FatalConditionHandler::oldSigActions[sizeof(signalDefs)/sizeof(SignalDefs)] = {};
     stack_t FatalConditionHandler::oldSigStack = {};
-    char FatalConditionHandler::altStackMem[SIGSTKSZ] = {};
 
 } // namespace Catch