diff --git a/Crashlytics/CHANGELOG.md b/Crashlytics/CHANGELOG.md
index a75b5675d85..ef5145db022 100644
--- a/Crashlytics/CHANGELOG.md
+++ b/Crashlytics/CHANGELOG.md
@@ -2,6 +2,7 @@
 - [added] Added stackFrameWithAddress API for recording custom errors that are symbolicated on the backend (#5975).
 - [fixed] Fixed comment typos (#6363).
 - [fixed] Remove device information from binary image data crash info entries (#6382).
+- [fixed] Fixed Apple Watch crash related to sigaction (#6434).
 
 # v4.5.0
 - [fixed] Fixed a compiler warning and removed unused networking code (#6210).
diff --git a/Crashlytics/Crashlytics/Components/FIRCLSContext.h b/Crashlytics/Crashlytics/Components/FIRCLSContext.h
index f94e633343d..c5a098f8254 100644
--- a/Crashlytics/Crashlytics/Components/FIRCLSContext.h
+++ b/Crashlytics/Crashlytics/Components/FIRCLSContext.h
@@ -57,7 +57,9 @@ typedef struct {
   FIRCLSBinaryImageReadOnlyContext binaryimage;
   FIRCLSExceptionReadOnlyContext exception;
   FIRCLSHostReadOnlyContext host;
+#if CLS_SIGNAL_SUPPORTED
   FIRCLSSignalReadContext signal;
+#endif
 #if CLS_MACH_EXCEPTION_SUPPORTED
   FIRCLSMachExceptionReadContext machException;
 #endif
diff --git a/Crashlytics/Crashlytics/Components/FIRCLSContext.m b/Crashlytics/Crashlytics/Components/FIRCLSContext.m
index d860e1fd34b..a7a20e75d23 100644
--- a/Crashlytics/Crashlytics/Components/FIRCLSContext.m
+++ b/Crashlytics/Crashlytics/Components/FIRCLSContext.m
@@ -196,12 +196,14 @@ bool FIRCLSContextInitialize(FIRCLSInternalReport* report,
   });
 
   if (!_firclsContext.readonly->debuggerAttached) {
+#if CLS_SIGNAL_SUPPORTED
     dispatch_group_async(group, queue, ^{
       _firclsContext.readonly->signal.path =
           FIRCLSContextAppendToRoot(rootPath, FIRCLSReportSignalFile);
 
       FIRCLSSignalInitialize(&_firclsContext.readonly->signal);
     });
+#endif
 
 #if CLS_MACH_EXCEPTION_SUPPORTED
     dispatch_group_async(group, queue, ^{
diff --git a/Crashlytics/Crashlytics/Controllers/FIRCLSReportManager.m b/Crashlytics/Crashlytics/Controllers/FIRCLSReportManager.m
index a5df5a655b9..cec76508221 100644
--- a/Crashlytics/Crashlytics/Controllers/FIRCLSReportManager.m
+++ b/Crashlytics/Crashlytics/Controllers/FIRCLSReportManager.m
@@ -507,7 +507,9 @@ - (void)crashReportingSetupCompleted:(FIRCLSProfileMark)mark {
   // check our handlers
   FIRCLSDispatchAfter(2.0, dispatch_get_main_queue(), ^{
     FIRCLSExceptionCheckHandlers((__bridge void *)(self));
+#if CLS_SIGNAL_SUPPORTED
     FIRCLSSignalCheckHandlers();
+#endif
 #if CLS_MACH_EXCEPTION_SUPPORTED
     FIRCLSMachExceptionCheckHandlers();
 #endif
diff --git a/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.c b/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.c
index e96ecfab13d..c82c47c2149 100644
--- a/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.c
+++ b/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.c
@@ -20,6 +20,7 @@
 #include <dlfcn.h>
 #include <stdlib.h>
 
+#if CLS_SIGNAL_SUPPORTED
 static const int FIRCLSFatalSignals[FIRCLSSignalCount] = {SIGABRT, SIGBUS, SIGFPE, SIGILL,
                                                           SIGSEGV, SIGSYS, SIGTRAP};
 
@@ -316,3 +317,4 @@ static void FIRCLSSignalHandler(int signal, siginfo_t *info, void *uapVoid) {
   // restore errno
   errno = savedErrno;
 }
+#endif
diff --git a/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.h b/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.h
index a4533a5cd73..46313de4a85 100644
--- a/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.h
+++ b/Crashlytics/Crashlytics/Handlers/FIRCLSSignal.h
@@ -20,8 +20,6 @@
 #include <signal.h>
 #include <stdbool.h>
 
-#define FIRCLSSignalCount (7)
-
 // per man sigaltstack, MINSIGSTKSZ is the minimum *overhead* needed to support
 // a signal stack.  The actual stack size must be larger.  Let's pick the recommended
 // size.
@@ -31,6 +29,9 @@
 #define CLS_SIGNAL_HANDLER_STACK_SIZE 0
 #endif
 
+#if CLS_SIGNAL_SUPPORTED
+#define FIRCLSSignalCount (7)
+
 typedef struct {
   const char* path;
   struct sigaction originalActions[FIRCLSSignalCount];
@@ -49,3 +50,4 @@ bool FIRCLSSignalSafeInstallPreexistingHandlers(FIRCLSSignalReadContext* roConte
 void FIRCLSSignalNameLookup(int number, int code, const char** name, const char** codeName);
 
 void FIRCLSSignalEnumerateHandledSignals(void (^block)(int idx, int signal));
+#endif
diff --git a/Crashlytics/Crashlytics/Helpers/FIRCLSFeatures.h b/Crashlytics/Crashlytics/Helpers/FIRCLSFeatures.h
index ba61233b5c5..fc90eea5c7a 100644
--- a/Crashlytics/Crashlytics/Helpers/FIRCLSFeatures.h
+++ b/Crashlytics/Crashlytics/Helpers/FIRCLSFeatures.h
@@ -23,6 +23,7 @@
 #define CLS_USE_SIGALTSTACK (!TARGET_OS_WATCH && !TARGET_OS_TV)
 #define CLS_CAN_SUSPEND_THREADS !TARGET_OS_WATCH
 #define CLS_MACH_EXCEPTION_SUPPORTED (!TARGET_OS_WATCH && !TARGET_OS_TV)
+#define CLS_SIGNAL_SUPPORTED !TARGET_OS_WATCH  // As of WatchOS 3, Signal crashes are not supported
 
 #define CLS_COMPACT_UNWINDING_SUPPORTED \
   ((CLS_CPU_I386 || CLS_CPU_X86_64 || CLS_CPU_ARM64) && CLS_COMPACT_UNWINDED_ENABLED)