diff --git a/tools/profiler/TableTicker.cpp b/tools/profiler/TableTicker.cpp
index 841ff140db7..378dd5bef09 100644
--- a/tools/profiler/TableTicker.cpp
+++ b/tools/profiler/TableTicker.cpp
@@ -580,7 +580,7 @@ void doSampleStackTrace(ProfileStack *aStack, ThreadProfile &aProfile, TickSampl
   // Sample
   // 's' tag denotes the start of a sample block
   // followed by 0 or more 'c' tags.
-  for (int i = 0; i < aStack->mStackPointer; i++) {
+  for (mozilla::sig_safe_t i = 0; i < aStack->mStackPointer; i++) {
     if (i == 0) {
       Address pc = 0;
       if (sample) {
diff --git a/tools/profiler/sps_sampler.h b/tools/profiler/sps_sampler.h
index 94c68ed3b01..5972a4cddcc 100644
--- a/tools/profiler/sps_sampler.h
+++ b/tools/profiler/sps_sampler.h
@@ -212,7 +212,8 @@ public:
     if (mQueueClearMarker) {
       clearMarkers();
     }
-    if (aMarkerId >= mMarkerPointer) {
+    if (aMarkerId < 0 ||
+	static_cast<mozilla::sig_safe_t>(aMarkerId) >= mMarkerPointer) {
       return NULL;
     }
     return mMarkers[aMarkerId];