diff --git a/mozilla/modules/libjar/Makefile.in b/mozilla/modules/libjar/Makefile.in
index 659265b7ce2..ad24814f0d3 100644
--- a/mozilla/modules/libjar/Makefile.in
+++ b/mozilla/modules/libjar/Makefile.in
@@ -58,6 +58,10 @@ EXPORTS		= $(MODULES_LIBJAR_LEXPORTS)
 
 include $(topsrcdir)/config/rules.mk
 
+ifeq ($(OS_ARCH), Linux)
+DEFINES		+= -D_BSD_SOURCE
+endif
+
 EXTRA_DSO_LDOPTS += \
 		-L$(DIST)/bin \
 		$(ZLIB_LIBS) \
diff --git a/mozilla/modules/libjar/standalone/Makefile.in b/mozilla/modules/libjar/standalone/Makefile.in
index f3d808ac1eb..76730b3b6aa 100644
--- a/mozilla/modules/libjar/standalone/Makefile.in
+++ b/mozilla/modules/libjar/standalone/Makefile.in
@@ -55,6 +55,10 @@ GARBAGE_DIRS += .deps
 
 include $(topsrcdir)/config/rules.mk
 
+ifeq ($(OS_ARCH), Linux)
+DEFINES	+= -D_BSD_SOURCE
+endif
+
 DEFINES += -DSTANDALONE
 
 # Make sure that these custom rules stay in sync with rules.mk