diff --git a/config/rules.mk b/config/rules.mk
index 5a36e8104ccd..d964b7077725 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -360,6 +360,10 @@ endif # GNU_CC
 endif # ENABLE_CXX_EXCEPTIONS
 endif # WINNT
 
+ifeq ($(SOLARIS_SUNPRO_CXX),1)
+CXXFLAGS += -features=extensions -D__FUNCTION__=__func__
+endif # Solaris Sun Studio C++
+
 ifeq (,$(filter-out WINNT WINCE,$(HOST_OS_ARCH)))
 HOST_PDBFILE=$(basename $(@F)).pdb
 endif
diff --git a/js/src/config/rules.mk b/js/src/config/rules.mk
index 5a36e8104ccd..d964b7077725 100644
--- a/js/src/config/rules.mk
+++ b/js/src/config/rules.mk
@@ -360,6 +360,10 @@ endif # GNU_CC
 endif # ENABLE_CXX_EXCEPTIONS
 endif # WINNT
 
+ifeq ($(SOLARIS_SUNPRO_CXX),1)
+CXXFLAGS += -features=extensions -D__FUNCTION__=__func__
+endif # Solaris Sun Studio C++
+
 ifeq (,$(filter-out WINNT WINCE,$(HOST_OS_ARCH)))
 HOST_PDBFILE=$(basename $(@F)).pdb
 endif
diff --git a/storage/test/Makefile.in b/storage/test/Makefile.in
index 09f09ba64385..d80706e358d7 100644
--- a/storage/test/Makefile.in
+++ b/storage/test/Makefile.in
@@ -77,7 +77,3 @@ LIBS = \
 	$(NULL)
 
 include $(topsrcdir)/config/rules.mk
-
-ifdef SOLARIS_SUNPRO_CXX
-CXXFLAGS += -features=extensions -D__FUNCTION__=__func__
-endif
diff --git a/xpcom/tests/Makefile.in b/xpcom/tests/Makefile.in
index 89ef47d591ba..79b42dfbddd5 100644
--- a/xpcom/tests/Makefile.in
+++ b/xpcom/tests/Makefile.in
@@ -146,10 +146,6 @@ ifeq ($(OS_ARCH)$(OS_RELEASE),FreeBSD2)
 LIBS		+= -lpcap
 endif
 
-ifdef SOLARIS_SUNPRO_CXX
-CXXFLAGS += -features=extensions -D__FUNCTION__=__func__
-endif
-
 ENABLE_CXX_EXCEPTIONS = 1
 
 XPCSHELL_TESTS = unit