diff --git a/libnativebridge/native_bridge.cc b/libnativebridge/native_bridge.cc
index c19aba9..d460f6f 100644
--- a/libnativebridge/native_bridge.cc
+++ b/libnativebridge/native_bridge.cc
@@ -205,6 +205,10 @@
 
 
 bool NeedsNativeBridge(const char* instruction_set) {
+  if (instruction_set == nullptr) {
+    ALOGE("Null instruction set in NeedsNativeBridge.");
+    return false;
+  }
   return strncmp(instruction_set, kRuntimeISA, strlen(kRuntimeISA) + 1) != 0;
 }
 
@@ -240,11 +244,16 @@
   // mount command will fail, so we safe the extra file existence check...
   char cpuinfo_path[1024];
 
-  snprintf(cpuinfo_path, 1024, "/system/lib"
+#ifdef HAVE_ANDROID_OS
+  snprintf(cpuinfo_path, sizeof(cpuinfo_path), "/system/lib"
 #ifdef __LP64__
-  "64"
+      "64"
+#endif  // __LP64__
+      "/%s/cpuinfo", instruction_set);
+#else   // !HAVE_ANDROID_OS
+  // To be able to test on the host, we hardwire a relative path.
+  snprintf(cpuinfo_path, sizeof(cpuinfo_path), "./cpuinfo");
 #endif
-    "/%s/cpuinfo", instruction_set);
 
   // Bind-mount.
   if (TEMP_FAILURE_RETRY(mount(cpuinfo_path,        // Source.
@@ -252,7 +261,7 @@
                                nullptr,             // FS type.
                                MS_BIND,             // Mount flags: bind mount.
                                nullptr)) == -1) {   // "Data."
-    ALOGW("Failed to bind-mount %s as /proc/cpuinfo: %d", cpuinfo_path, errno);
+    ALOGW("Failed to bind-mount %s as /proc/cpuinfo: %s", cpuinfo_path, strerror(errno));
   }
 #else
   UNUSED(instruction_set);
diff --git a/libnativebridge/tests/Android.mk b/libnativebridge/tests/Android.mk
index f58b8f7..a94d2f7 100644
--- a/libnativebridge/tests/Android.mk
+++ b/libnativebridge/tests/Android.mk
@@ -5,6 +5,8 @@
 # Build the unit tests.
 test_src_files := \
     InvalidCharsNativeBridge_test.cpp \
+    NeedsNativeBridge_test.cpp \
+    PreInitializeNativeBridge_test.cpp \
     ReSetupNativeBridge_test.cpp \
     UnavailableNativeBridge_test.cpp \
     ValidNameNativeBridge_test.cpp
diff --git a/libnativebridge/tests/NeedsNativeBridge_test.cpp b/libnativebridge/tests/NeedsNativeBridge_test.cpp
new file mode 100644
index 0000000..e1c0876
--- /dev/null
+++ b/libnativebridge/tests/NeedsNativeBridge_test.cpp
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "NativeBridgeTest.h"
+
+namespace android {
+
+static const char* kISAs[] = { "arm", "arm64", "mips", "x86", "x86_64", "random", "64arm", "64_x86",
+                               "64_x86_64", "", "reallylongstringabcd", nullptr };
+
+#if defined(__arm__)
+static const char* kRuntimeISA = "arm";
+#elif defined(__aarch64__)
+static const char* kRuntimeISA = "arm64";
+#elif defined(__mips__)
+static const char* kRuntimeISA = "mips";
+#elif defined(__i386__)
+static const char* kRuntimeISA = "x86";
+#elif defined(__x86_64__)
+static const char* kRuntimeISA = "x86_64";
+#else
+static const char* kRuntimeISA = "unknown";
+#endif
+
+TEST_F(NativeBridgeTest, NeedsNativeBridge) {
+    EXPECT_EQ(false, NeedsNativeBridge(kRuntimeISA));
+
+    const size_t kISACount = sizeof(kISAs)/sizeof(kISAs[0]);
+    for (size_t i = 0; i < kISACount; i++) {
+        EXPECT_EQ(kISAs[i] == nullptr ? false : strcmp(kISAs[i], kRuntimeISA) != 0,
+                  NeedsNativeBridge(kISAs[i]));
+    }
+}
+
+}  // namespace android
diff --git a/libnativebridge/tests/PreInitializeNativeBridge_test.cpp b/libnativebridge/tests/PreInitializeNativeBridge_test.cpp
new file mode 100644
index 0000000..9b487d7
--- /dev/null
+++ b/libnativebridge/tests/PreInitializeNativeBridge_test.cpp
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "NativeBridgeTest.h"
+
+#include <cstdio>
+#include <cstring>
+#include <cutils/log.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+
+namespace android {
+
+static constexpr const char* kTestData = "PreInitializeNativeBridge test.";
+
+TEST_F(NativeBridgeTest, PreInitializeNativeBridge) {
+#ifndef __APPLE_         // Mac OS does not support bind-mount.
+#ifndef HAVE_ANDROID_OS  // Cannot write into the hard-wired location.
+    // Try to create our mount namespace.
+    if (unshare(CLONE_NEWNS) != -1) {
+        // Create a dummy file.
+        FILE* cpuinfo = fopen("./cpuinfo", "w");
+        ASSERT_NE(nullptr, cpuinfo) << strerror(errno);
+        fprintf(cpuinfo, kTestData);
+        fclose(cpuinfo);
+
+        // Call the setup.
+        PreInitializeNativeBridge("does not matter 1", "short 2");
+
+        // Read /proc/cpuinfo
+        FILE* proc_cpuinfo = fopen("/proc/cpuinfo", "r");
+        ASSERT_NE(nullptr, proc_cpuinfo) << strerror(errno);
+        char buf[1024];
+        EXPECT_NE(nullptr, fgets(buf, sizeof(buf), proc_cpuinfo)) << "Error reading.";
+        fclose(proc_cpuinfo);
+
+        EXPECT_EQ(0, strcmp(buf, kTestData));
+
+        // Delete the file.
+        ASSERT_EQ(0, unlink("./cpuinfo")) << "Error unlinking temporary file.";
+        // Ending the test will tear down the mount namespace.
+    } else {
+        GTEST_LOG_(WARNING) << "Could not create mount namespace. Are you running this as root?";
+    }
+#endif
+#endif
+}
+
+}  // namespace android