diff --git a/.gitignore b/.gitignore
index 265b1b2..38d2692 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,4 @@
 .*~
 *.pyc
 help.html
-v8shell
+jsshell
diff --git a/Makefile b/Makefile
index 4c3e927..6a6b181 100644
--- a/Makefile
+++ b/Makefile
@@ -2,8 +2,12 @@
 
 all: help.html
 
-v8shell: v8shell.cc
-	g++ -o $@ $< -lv8
+MACOS_JS_PATH=/System/Library/Frameworks/JavaScriptCore.framework/Versions/Current/Resources/jsc
+jsshell:
+	rm -f $@
+	[ -e "${MACOS_JS_PATH}" ] && \
+	ln -s "${MACOS_JS_PATH}" jsshell || \
+	g++ -o $@ v8shell.cc -lv8
 
 runtests: $(patsubst %.js,%.js.run,$(wildcard t/t*.js))
 
@@ -11,12 +15,12 @@
 	markdown $< >$@.new
 	mv $@.new $@
 
-%.js.run: %.js v8shell
-	./v8shell wvtest.js $*.js
+%.js.run: %.js jsshell
+	./jsshell wvtest.js $*.js
 
-test: v8shell
+test: jsshell
 	./wvtestrun $(MAKE) runtests
 
 clean:
-	rm -f *~ .*~ */*~ */.*~ help.html v8shell
+	rm -f *~ .*~ */*~ */.*~ help.html v8shell jsshell
 	find . -name '*~' -exec rm -f {} \;
diff --git a/wvtest.js b/wvtest.js
index 3a1008c..3fb8120 100644
--- a/wvtest.js
+++ b/wvtest.js
@@ -4,16 +4,26 @@
 function lookup(filename, line) {
     var f = files[filename];
     if (!f) {
-	f = files[filename] = read(filename).split('\n');
+        try {
+            f = files[filename] = read(filename).split('\n');
+        } catch (e) {
+            f = files[filename] = [];
+        }
     }
-    return f[line-1]; // file line numbers are 1-based
+    return f[line-1] || 'BAD_LINE'; // file line numbers are 1-based
 }
 
 
+// TODO(apenwarr): Right now this only really works right on chrome.
+// Maybe take some advice from this article:
+//  http://stackoverflow.com/questions/5358983/javascript-stack-inspection-on-safari-mobile-ipad
 function trace() {
     var FILELINE_RE = /[\b\s]\(?([^:\s]+):(\d+)/;
     var out = [];
     var e = Error().stack;
+    if (!e) {
+        return [['UNKNOWN', 0], ['UNKNOWN', 0]];
+    }
     var lines = e.split('\n');
     for (i in lines) {
 	if (i > 2) {