diff --git a/linker/Android.mk b/linker/Android.mk
index b757030..5fccf9b 100644
--- a/linker/Android.mk
+++ b/linker/Android.mk
@@ -8,21 +8,21 @@
 endif
 
 LOCAL_SRC_FILES:= \
-	arch/$(TARGET_ARCH)/begin.$(linker_begin_extension) \
-	debugger.cpp \
-	dlfcn.cpp \
-	linker.cpp \
-	linker_environ.cpp \
-	linker_format.cpp \
-	linker_phdr.cpp \
-	rt.cpp
+    arch/$(TARGET_ARCH)/begin.$(linker_begin_extension) \
+    debugger.cpp \
+    dlfcn.cpp \
+    linker.cpp \
+    linker_environ.cpp \
+    linker_format.cpp \
+    linker_phdr.cpp \
+    rt.cpp
 
 LOCAL_LDFLAGS := -shared
 
 LOCAL_CFLAGS += -fno-stack-protector \
         -Wstrict-overflow=5 \
         -fvisibility=hidden \
-        -Wall -Wextra
+        -Wall -Wextra -Werror
 
 # We need to access Bionic private headers in the linker...
 LOCAL_CFLAGS += -I$(LOCAL_PATH)/../libc/
diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp
index 24006e2..2184f3a 100644
--- a/linker/dlfcn.cpp
+++ b/linker/dlfcn.cpp
@@ -55,9 +55,9 @@
   return old_value;
 }
 
-void* dlopen(const char* filename, int flag) {
+void* dlopen(const char* filename, int flags) {
   ScopedPthreadMutexLocker locker(&gDlMutex);
-  soinfo* result = do_dlopen(filename);
+  soinfo* result = do_dlopen(filename, flags);
   if (result == NULL) {
     __bionic_format_dlerror("dlopen failed", linker_get_error());
     return NULL;
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 0d0a8a9..0bdff99 100755
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -966,7 +966,11 @@
   return 0;
 }
 
-soinfo* do_dlopen(const char* name) {
+soinfo* do_dlopen(const char* name, int flags) {
+  if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL)) != 0) {
+    DL_ERR("invalid flags to dlopen: %x", flags);
+    return NULL;
+  }
   set_soinfo_pool_protection(PROT_READ | PROT_WRITE);
   soinfo* si = find_library(name);
   if (si != NULL) {
diff --git a/linker/linker.h b/linker/linker.h
index 51869e7..60c76fa 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -207,7 +207,7 @@
 #define DT_PREINIT_ARRAYSZ 33
 #endif
 
-soinfo* do_dlopen(const char* name);
+soinfo* do_dlopen(const char* name, int flags);
 int do_dlclose(soinfo* si);
 
 Elf32_Sym* lookup(const char* name, soinfo** found, soinfo* start);
diff --git a/tests/Android.mk b/tests/Android.mk
index abc6f52..7153383 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -68,7 +68,7 @@
 
 test_dynamic_ldflags = -Wl,--export-dynamic -Wl,-u,DlSymTestFunction
 test_dynamic_src_files = \
-    dlopen_test.cpp \
+    dlfcn_test.cpp \
 
 # Build tests for the device (with bionic's .so). Run with:
 #   adb shell /data/nativetest/bionic-unit-tests/bionic-unit-tests
diff --git a/tests/dlopen_test.cpp b/tests/dlfcn_test.cpp
similarity index 87%
rename from tests/dlopen_test.cpp
rename to tests/dlfcn_test.cpp
index f042503..0c40eb7 100644
--- a/tests/dlopen_test.cpp
+++ b/tests/dlfcn_test.cpp
@@ -32,7 +32,7 @@
   gCalled = true;
 }
 
-TEST(dlopen, dlsym_in_self) {
+TEST(dlfcn, dlsym_in_self) {
   dlerror(); // Clear any pending errors.
   void* self = dlopen(NULL, RTLD_NOW);
   ASSERT_TRUE(self != NULL);
@@ -50,7 +50,7 @@
   ASSERT_EQ(0, dlclose(self));
 }
 
-TEST(dlopen, dlopen_failure) {
+TEST(dlfcn, dlopen_failure) {
   void* self = dlopen("/does/not/exist", RTLD_NOW);
   ASSERT_TRUE(self == NULL);
 #if __BIONIC__
@@ -65,7 +65,7 @@
   return reinterpret_cast<void*>(strdup(dlerror()));
 }
 
-TEST(dlopen, dlerror_concurrent) {
+TEST(dlfcn, dlerror_concurrent) {
   dlopen("/main/thread", RTLD_NOW);
   const char* main_thread_error = dlerror();
   ASSERT_SUBSTR("/main/thread", main_thread_error);
@@ -81,7 +81,7 @@
   ASSERT_SUBSTR("/main/thread", main_thread_error);
 }
 
-TEST(dlopen, dlsym_failures) {
+TEST(dlfcn, dlsym_failures) {
   dlerror(); // Clear any pending errors.
   void* self = dlopen(NULL, RTLD_NOW);
   ASSERT_TRUE(self != NULL);
@@ -114,7 +114,7 @@
   ASSERT_EQ(0, dlclose(self));
 }
 
-TEST(dlopen, dladdr) {
+TEST(dlfcn, dladdr) {
   dlerror(); // Clear any pending errors.
   void* self = dlopen(NULL, RTLD_NOW);
   ASSERT_TRUE(self != NULL);
@@ -174,7 +174,7 @@
   ASSERT_EQ(0, dlclose(self));
 }
 
-TEST(dlopen, dladdr_invalid) {
+TEST(dlfcn, dladdr_invalid) {
   Dl_info info;
 
   dlerror(); // Clear any pending errors.
@@ -190,10 +190,31 @@
 
 #if __BIONIC__
 // Our dynamic linker doesn't support GNU hash tables.
-TEST(dlopen, library_with_only_gnu_hash) {
+TEST(dlfcn, dlopen_library_with_only_gnu_hash) {
   dlerror(); // Clear any pending errors.
   void* handle = dlopen("no-elf-hash-table-library.so", RTLD_NOW);
   ASSERT_TRUE(handle == NULL);
   ASSERT_STREQ("dlopen failed: empty/missing DT_HASH in \"no-elf-hash-table-library.so\" (built with --hash-style=gnu?)", dlerror());
 }
 #endif
+
+TEST(dlfcn, dlopen_bad_flags) {
+  dlerror(); // Clear any pending errors.
+  void* handle;
+
+#ifdef __GLIBC__
+  // glibc was smart enough not to define RTLD_NOW as 0, so it can detect missing flags.
+  handle = dlopen(NULL, 0);
+  ASSERT_TRUE(handle == NULL);
+  ASSERT_SUBSTR("invalid", dlerror());
+#endif
+
+  handle = dlopen(NULL, 0xffffffff);
+  ASSERT_TRUE(handle == NULL);
+  ASSERT_SUBSTR("invalid", dlerror());
+
+  // glibc actually allows you to choose both RTLD_NOW and RTLD_LAZY at the same time, and so do we.
+  handle = dlopen(NULL, RTLD_NOW|RTLD_LAZY);
+  ASSERT_TRUE(handle != NULL);
+  ASSERT_SUBSTR(NULL, dlerror());
+}