diff --git a/ReactCommon/cxxreact/tests/BUCK b/ReactCommon/cxxreact/tests/BUCK
index e9ae81aa21a..b123414e910 100644
--- a/ReactCommon/cxxreact/tests/BUCK
+++ b/ReactCommon/cxxreact/tests/BUCK
@@ -55,3 +55,17 @@ fb_xplat_cxx_test(
         react_native_xplat_target("cxxreact:jsbigstring"),
     ],
 )
+
+fb_xplat_cxx_test(
+    name = "jsbigstring_test",
+    srcs = ["jsbigstring.cpp"],
+    compiler_flags = [
+        "-fexceptions",
+        "-frtti",
+    ],
+    deps = [
+        "fbsource//xplat/folly:molly",
+        "fbsource//xplat/third-party/gmock:gtest",
+        react_native_xplat_target("cxxreact:jsbigstring"),
+    ],
+)
diff --git a/ReactCommon/cxxreact/tests/jsbigstring.cpp b/ReactCommon/cxxreact/tests/jsbigstring.cpp
index 69e265c96f0..a8f58f16646 100644
--- a/ReactCommon/cxxreact/tests/jsbigstring.cpp
+++ b/ReactCommon/cxxreact/tests/jsbigstring.cpp
@@ -15,7 +15,10 @@ using namespace facebook::react;
 namespace {
 int tempFileFromString(std::string contents)
 {
-  std::string tmp {getenv("TMPDIR")};
+  const char *tmpDir = getenv("TMPDIR");
+  if (tmpDir == nullptr)
+    tmpDir = "/tmp";
+  std::string tmp {tmpDir};
   tmp += "/temp.XXXXXX";
 
   std::vector<char> tmpBuf {tmp.begin(), tmp.end()};