diff --git a/src/bin/debug/strace/signals.cpp b/src/bin/debug/strace/signals.cpp
index d517178b2f..3a2165d93d 100644
--- a/src/bin/debug/strace/signals.cpp
+++ b/src/bin/debug/strace/signals.cpp
@@ -9,6 +9,11 @@
 #include <string>
 
 #include "signals.h"
+#include "strace.h"
+#include "Context.h"
+#include "MemoryReader.h"
+#include "Syscall.h"
+#include "TypeHandler.h"
 
 
 // signal names
@@ -49,6 +54,67 @@ static const char *kSignalName[] = {
 };
 
 
+struct enum_info {
+	int index;
+	const char *name;
+};
+
+#define ENUM_INFO_ENTRY(name) \
+	{ name, #name }
+
+static const enum_info kSigmaskHow[] = {
+	ENUM_INFO_ENTRY(SIG_BLOCK),
+	ENUM_INFO_ENTRY(SIG_UNBLOCK),
+	ENUM_INFO_ENTRY(SIG_SETMASK),
+
+	{ 0, NULL }
+};
+
+
+#define sigmask(sig) (1 << ((sig) - 1))
+#define FLAG_INFO_ENTRY(name) \
+	{ sigmask( SIG##name ), #name }
+
+static const FlagsTypeHandler::FlagInfo kSigmaskFlagsInfo[] = {
+	FLAG_INFO_ENTRY(HUP),
+	FLAG_INFO_ENTRY(INT),
+	FLAG_INFO_ENTRY(QUIT),
+	FLAG_INFO_ENTRY(ILL),
+	FLAG_INFO_ENTRY(CHLD),
+	FLAG_INFO_ENTRY(ABRT),
+	FLAG_INFO_ENTRY(PIPE),
+	FLAG_INFO_ENTRY(FPE),
+	FLAG_INFO_ENTRY(KILL),
+	FLAG_INFO_ENTRY(STOP),
+	FLAG_INFO_ENTRY(SEGV),
+	FLAG_INFO_ENTRY(CONT),
+	FLAG_INFO_ENTRY(TSTP),
+	FLAG_INFO_ENTRY(ALRM),
+	FLAG_INFO_ENTRY(TERM),
+	FLAG_INFO_ENTRY(TTIN),
+	FLAG_INFO_ENTRY(TTOU),
+	FLAG_INFO_ENTRY(USR1),
+	FLAG_INFO_ENTRY(USR2),
+	FLAG_INFO_ENTRY(WINCH),
+	FLAG_INFO_ENTRY(KILLTHR),
+	FLAG_INFO_ENTRY(TRAP),
+	FLAG_INFO_ENTRY(POLL),
+	FLAG_INFO_ENTRY(PROF),
+	FLAG_INFO_ENTRY(SYS),
+	FLAG_INFO_ENTRY(URG),
+	FLAG_INFO_ENTRY(VTALRM),
+	FLAG_INFO_ENTRY(XCPU),
+	FLAG_INFO_ENTRY(XFSZ),
+	FLAG_INFO_ENTRY(BUS),
+
+	{ 0, NULL }
+};
+
+
+static FlagsTypeHandler::FlagsList kSigmaskFlags;
+static EnumTypeHandler::EnumMap kSigmaskHowMap;
+
+
 std::string
 signal_name(int signal)
 {
@@ -199,3 +265,88 @@ signal_info(siginfo_t& info)
 
 	return string;
 }
+
+
+class SigsetTypeHandler : public FlagsTypeHandler {
+public:
+	SigsetTypeHandler()
+		:
+		FlagsTypeHandler(kSigmaskFlags)
+	{
+	}
+
+	string GetParameterValue(Context &context, Parameter *param,
+		const void *address)
+	{
+		void *data = *(void **)address;
+
+		if (context.GetContents(Context::POINTER_VALUES)) {
+			int32 bytesRead;
+			sigset_t value;
+			status_t err = context.Reader().Read(data, &value, sizeof(value), bytesRead);
+			if (err != B_OK)
+				return context.FormatPointer(data);
+
+			uint32 count = 0;
+#if __GNUC__ > 2
+                count += __builtin_popcount(value);
+#else
+			{
+				sigset_t mask = value;
+				while (mask > 0) {
+					if ((mask & 1) == 1)
+						count++;
+					mask >>= 1;
+				}
+			}
+#endif
+			string r;
+			// when more than 2/3 of the signals are set, inverse
+			if (count > SIGRESERVED2 * 2 / 3) {
+				value = ~value;
+				r += "~";
+			}
+			value &= (((sigset_t)1 << SIGRESERVED2) - 1);
+
+			r += "[";
+			r += RenderValue(context, value);
+			r += "]";
+			return r;
+		}
+
+		return context.FormatPointer(data);
+	}
+
+	string GetReturnValue(Context &context, uint64 value)
+	{
+		return context.FormatPointer((void *)value);
+	}
+};
+
+
+void
+patch_signal()
+{
+	for (int i = 0; kSigmaskFlagsInfo[i].name != NULL; i++)
+		kSigmaskFlags.push_back(kSigmaskFlagsInfo[i]);
+	for (int i = 0; kSigmaskHow[i].name != NULL; i++) {
+		kSigmaskHowMap[kSigmaskHow[i].index] = kSigmaskHow[i].name;
+	}
+	Syscall *setSignalMask = get_syscall("_kern_set_signal_mask");
+	setSignalMask->GetParameter("how")->SetHandler(new EnumTypeHandler(kSigmaskHowMap));
+	setSignalMask->GetParameter("set")->SetHandler(new SigsetTypeHandler());
+	setSignalMask->GetParameter("oldSet")->SetHandler(new SigsetTypeHandler());
+	setSignalMask->GetParameter("oldSet")->SetOut(true);
+
+	Syscall *sigwait = get_syscall("_kern_sigwait");
+	sigwait->GetParameter("set")->SetHandler(new SigsetTypeHandler());
+	sigwait->GetParameter("info")->SetOut(true);
+
+	Syscall *sigsuspend = get_syscall("_kern_sigsuspend");
+	sigsuspend->GetParameter("mask")->SetHandler(new SigsetTypeHandler());
+
+	Syscall *sigpending = get_syscall("_kern_sigpending");
+	sigpending->GetParameter("set")->SetHandler(new SigsetTypeHandler());
+	sigpending->GetParameter("set")->SetOut(true);
+
+}
diff --git a/src/bin/debug/strace/strace.cpp b/src/bin/debug/strace/strace.cpp
index 9577263293..11531adffa 100644
--- a/src/bin/debug/strace/strace.cpp
+++ b/src/bin/debug/strace/strace.cpp
@@ -238,6 +238,7 @@ patch_syscalls()
 	extern void patch_mutex();
 	extern void patch_network();
 	extern void patch_rlimit();
+	extern void patch_signal();
 
 	for (size_t i = 0; i < sSyscallVector.size(); i++) {
 		Syscall *syscall = sSyscallVector[i];
@@ -261,6 +262,7 @@ patch_syscalls()
 	patch_mutex();
 	patch_network();
 	patch_rlimit();
+	patch_signal();
 }