diff --git a/ef/config/FreeBSD.mk b/ef/config/FreeBSD.mk
index f0d62b83c7ca..1a302ef62c28 100644
--- a/ef/config/FreeBSD.mk
+++ b/ef/config/FreeBSD.mk
@@ -26,6 +26,7 @@ else
 CPU_ARCH		:= $(OS_TEST)
 endif
 
+IMPL_STRATEGY		= _EMU
 DEFAULT_COMPILER		= gcc
 CC				= gcc
 CXX				= g++
diff --git a/ef/config/UNIX.mk b/ef/config/UNIX.mk
index e1f59c73e9ba..3acf1ccfa8be 100644
--- a/ef/config/UNIX.mk
+++ b/ef/config/UNIX.mk
@@ -31,9 +31,12 @@ endif
 #
 # Name of the binary code directories
 #
+ifndef IMPL_STRATEGY
+IMPL_STRATEGY		= _PTH
+endif
 
 OBJDIR_NAME	= $(OS_TARGET)$(CPU_ARCH_TAG)$(OBJDIR_TAG).OBJ
-NSPR_OBJDIR     = $(OS_CONFIG)$(CPU_ARCH_TAG)_PTH$(OBJDIR_TAG).OBJ
+NSPR_OBJDIR     = $(OS_CONFIG)$(CPU_ARCH_TAG)$(IMPL_STRATEGY)$(OBJDIR_TAG).OBJ
 
 #
 # Install