diff --git a/R/tbb.R b/R/tbb.R
index 27cf3bba..00fccd3b 100644
--- a/R/tbb.R
+++ b/R/tbb.R
@@ -75,7 +75,7 @@ tbbCxxFlags <- function() {
 tbbLdFlags <- function() {
    
    # shortcut if TBB_LIB defined
-   tbbLib <- Sys.getenv("TBB_LIB", unset = TBB_LIB)
+   tbbLib <- Sys.getenv("TBB_LINK_LIB", Sys.getenv("TBB_LIB", unset = TBB_LIB))
    if (nzchar(tbbLib)) {
       fmt <- "-L%1$s -Wl,-rpath,%1$s -ltbb -ltbbmalloc"
       return(sprintf(fmt, asBuildPath(tbbLib)))
diff --git a/src/Makevars.in b/src/Makevars.in
index 75670079..83e78fb3 100644
--- a/src/Makevars.in
+++ b/src/Makevars.in
@@ -40,6 +40,7 @@ else
 
 	ifeq ($(UNAME), Darwin)
 		USE_TBB=Mac
+		MAKE_ARGS += arch=$(shell uname -m)
 	endif
 
 	ifeq ($(UNAME), Linux)