diff --git a/src/runtime/pprof/proto.go b/src/runtime/pprof/proto.go
index 1cf3a51..cbd0b83 100644
--- a/src/runtime/pprof/proto.go
+++ b/src/runtime/pprof/proto.go
@@ -54,6 +54,7 @@
 	file, buildID string
 
 	funcs symbolizeFlag
+	fake  bool // map entry was faked; /proc/self/maps wasn't available
 }
 
 // symbolizeFlag keeps track of symbolization result.
@@ -267,7 +268,7 @@
 		frame, more = frames.Next()
 	}
 	for i := range b.mem {
-		if b.mem[i].start <= addr && addr < b.mem[i].end {
+		if b.mem[i].start <= addr && addr < b.mem[i].end || b.mem[i].fake {
 			b.pb.uint64Opt(tagLocation_MappingID, uint64(i+1))
 
 			m := b.mem[i]
@@ -440,6 +441,12 @@
 func (b *profileBuilder) readMapping() {
 	data, _ := ioutil.ReadFile("/proc/self/maps")
 	parseProcSelfMaps(data, b.addMapping)
+	if len(b.mem) == 0 { // pprof expects a map entry, so fake one.
+		b.addMappingEntry(0, 0, 0, "", "", true)
+		// TODO(hyangah): make addMapping return *memMap or
+		// take a memMap struct, and get rid of addMappingEntry
+		// that takes a bunch of positional arguments.
+	}
 }
 
 func parseProcSelfMaps(data []byte, addMapping func(lo, hi, offset uint64, file, buildID string)) {
@@ -540,11 +547,16 @@
 }
 
 func (b *profileBuilder) addMapping(lo, hi, offset uint64, file, buildID string) {
+	b.addMappingEntry(lo, hi, offset, file, buildID, false)
+}
+
+func (b *profileBuilder) addMappingEntry(lo, hi, offset uint64, file, buildID string, fake bool) {
 	b.mem = append(b.mem, memMap{
 		start:   uintptr(lo),
 		end:     uintptr(hi),
 		offset:  offset,
 		file:    file,
 		buildID: buildID,
+		fake:    fake,
 	})
 }
diff --git a/src/runtime/pprof/proto_test.go b/src/runtime/pprof/proto_test.go
index 36c345b..76bd46d 100644
--- a/src/runtime/pprof/proto_test.go
+++ b/src/runtime/pprof/proto_test.go
@@ -97,9 +97,16 @@
 		addr2 = mprof.Mapping[1].Start
 		map2 = mprof.Mapping[1]
 		map2.BuildID, _ = elfBuildID(map2.File)
+	case "js":
+		addr1 = uint64(funcPC(f1))
+		addr2 = uint64(funcPC(f2))
 	default:
 		addr1 = uint64(funcPC(f1))
 		addr2 = uint64(funcPC(f2))
+		// Fake mapping - HasFunctions will be true because two PCs from Go
+		// will be fully symbolized.
+		fake := &profile.Mapping{ID: 1, HasFunctions: true}
+		map1, map2 = fake, fake
 	}
 	return
 }
@@ -301,3 +308,41 @@
 	}
 	return true
 }
+
+// TestFakeMapping tests if at least one mapping exists
+// (including a fake mapping), and their HasFunctions bits
+// are set correctly.
+func TestFakeMapping(t *testing.T) {
+	var buf bytes.Buffer
+	if err := Lookup("heap").WriteTo(&buf, 0); err != nil {
+		t.Fatalf("failed to write heap profile: %v", err)
+	}
+	prof, err := profile.Parse(&buf)
+	if err != nil {
+		t.Fatalf("failed to parse the generated profile data: %v", err)
+	}
+	t.Logf("Profile: %s", prof)
+	if len(prof.Mapping) == 0 {
+		t.Fatal("want profile with at least one mapping entry, got 0 mapping")
+	}
+
+	hit := make(map[*profile.Mapping]bool)
+	miss := make(map[*profile.Mapping]bool)
+	for _, loc := range prof.Location {
+		if symbolized(loc) {
+			hit[loc.Mapping] = true
+		} else {
+			miss[loc.Mapping] = true
+		}
+	}
+	for _, m := range prof.Mapping {
+		if miss[m] && m.HasFunctions {
+			t.Errorf("mapping %+v has HasFunctions=true, but contains locations with failed symbolization", m)
+			continue
+		}
+		if !miss[m] && hit[m] && !m.HasFunctions {
+			t.Errorf("mapping %+v has HasFunctions=false, but all referenced locations from this lapping were symbolized successfully", m)
+			continue
+		}
+	}
+}