diff --git a/modules/libutil/public/makefile.win b/modules/libutil/public/makefile.win
index 6adf5902bd63..a559cc3b41f7 100644
--- a/modules/libutil/public/makefile.win
+++ b/modules/libutil/public/makefile.win
@@ -20,6 +20,9 @@
 
 MODULE=util 
 DEPTH=..\..\.. 
-EXPORTS=xp_obs.h
+EXPORTS=xp_obs.h \
+!if defined(MOZ_PERF)
+stopwatch.h
+!endif
 
 !include $(DEPTH)\config\rules.mak
diff --git a/modules/libutil/src/makefile.win b/modules/libutil/src/makefile.win
index 08531e9611cf..e10d5ef48944 100644
--- a/modules/libutil/src/makefile.win
+++ b/modules/libutil/src/makefile.win
@@ -18,10 +18,15 @@
 MODULE=util 
 DEPTH=..\..\.. 
 CSRCS=obs.c 
+!if defined(MOZ_PERF)
+CPPSRCS=stopwatch.cpp
+CPP_OBJS=.\$(OBJDIR)\stopwatch.obj
+!endif
 REQUIRES=nspr util 
 LIBRARY_NAME=util 
 C_OBJS=.\$(OBJDIR)\obs.obj 
 
+
 !include $(DEPTH)\config\rules.mak
 
 install::  $(LIBRARY)