diff --git a/src/dbi.cpp b/src/dbi.cpp
index bb5d28261..975b8009b 100644
--- a/src/dbi.cpp
+++ b/src/dbi.cpp
@@ -172,6 +172,12 @@ NAPI_FUNCTION(getByBinary) {
 	GET_UINT32_ARG(keySize, 1);
 	RETURN_INT32(dw->doGetByBinary(keySize));
 }
+
+extern "C" EXTERN uint32_t dbiGetByBinary(double dwPointer, uint32_t keySize) {
+    DbiWrap* dw = (DbiWrap*) (size_t) dwPointer;
+    return dw->doGetByBinary(keySize);
+}
+
 napi_finalize noopDbi = [](napi_env, void *, void *) {
 	// Data belongs to LMDB, we shouldn't free it here
 };
diff --git a/src/lmdb-js.h b/src/lmdb-js.h
index 3012c2d46..9c8d3a0d8 100644
--- a/src/lmdb-js.h
+++ b/src/lmdb-js.h
@@ -40,6 +40,12 @@ using namespace Napi;
 #ifndef __CPTHREAD_H__
 #define __CPTHREAD_H__
 
+#ifdef _WIN32
+#define EXTERN __declspec(dllexport)
+# else
+#define EXTERN __attribute__((visibility("default")))
+#endif
+
 #ifdef _WIN32
 # include <windows.h>
 #else