diff --git a/src/Makefile b/src/Makefile
index a76dc4b..fc47037 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -3,6 +3,11 @@ TOPDIR = $(realpath ..)
 
 CPPFLAGS = -Iinclude -I/usr/include/json-c
 FLAGS = -fPIC -Wall -g
+
+ifneq ($(CUSTOM_METADATA_ENDPOINT),)
+FLAGS += -DCUSTOM_METADATA_ENDPOINT=$(CUSTOM_METADATA_ENDPOINT)
+endif
+
 CFLAGS = $(FLAGS) -Wstrict-prototypes
 CXXFLAGS = $(FLAGS)
 
diff --git a/src/include/oslogin_utils.h b/src/include/oslogin_utils.h
index 4a24ecf..ac4bca5 100644
--- a/src/include/oslogin_utils.h
+++ b/src/include/oslogin_utils.h
@@ -49,8 +49,15 @@ using std::vector;
 namespace oslogin_utils {
 
 // Metadata server URL.
+#ifdef CUSTOM_METADATA_ENDPOINT
+#define Q(x) #x
+#define QUOTE(x) Q(x)
+static const char kMetadataServerUrl[] =
+    "http://" QUOTE(CUSTOM_METADATA_ENDPOINT) "/computeMetadata/v1/oslogin/";
+#else
 static const char kMetadataServerUrl[] =
     "http://169.254.169.254/computeMetadata/v1/oslogin/";
+#endif /* CUSTOM_METADATA_ENDPOINT */
 
 // BufferManager encapsulates and manages a buffer and length. This class is not
 // thread safe.