diff --git a/envsetup.sh b/envsetup.sh
index 8f9dfdb..140f80c 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -2096,14 +2096,20 @@
 }
 
 function mka() {
-    case `uname -s` in
-        Darwin)
-            make -j `sysctl hw.ncpu|cut -d" " -f2` "$@"
-            ;;
-        *)
-            mk_timer schedtool -B -n 1 -e ionice -n 1 make -j$(cat /proc/cpuinfo | grep "^processor" | wc -l) "$@"
-            ;;
-    esac
+    local T=$(gettop)
+    if [ "$T" ]; then
+        case `uname -s` in
+            Darwin)
+                make -C $T -j `sysctl hw.ncpu|cut -d" " -f2` "$@"
+                ;;
+            *)
+                mk_timer schedtool -B -n 1 -e ionice -n 1 make -C $T -j$(cat /proc/cpuinfo | grep "^processor" | wc -l) "$@"
+                ;;
+        esac
+
+    else
+        echo "Couldn't locate the top of the tree.  Try setting TOP."
+    fi
 }
 
 function cmka() {