diff --git a/src/stdafx.h b/src/stdafx.h
index 6e19bb6393..9d952c106f 100644
--- a/src/stdafx.h
+++ b/src/stdafx.h
@@ -394,6 +394,10 @@ void NORETURN AssertFailedError(int line, const char *file, const char *expressi
 #	define assert(expression) if (unlikely(!(expression))) AssertFailedError(__LINE__, __FILE__, #expression);
 #endif
 
+/* Define JSON_ASSERT, which is used by nlohmann-json. Otherwise the header-file
+ * will re-include assert.h, and reset the assert macro. */
+#define JSON_ASSERT(x) assert(x)
+
 #if defined(MAX_PATH)
 	/* It's already defined, no need to override */
 #elif defined(PATH_MAX) && PATH_MAX > 0