diff --git a/src/port/GBIMiddleware.cpp b/src/port/GBIMiddleware.cpp
index a3055edd..5e35e312 100644
--- a/src/port/GBIMiddleware.cpp
+++ b/src/port/GBIMiddleware.cpp
@@ -3,7 +3,7 @@
 #include "Engine.h"
 #include "DisplayList.h"
 
-extern "C" int GameEngine_OTRSigCheck(const char* data);
+extern "C" uint8_t GameEngine_OTRSigCheck(const char* data);
 
 extern "C" void gSPDisplayList(Gfx* pkt, Gfx* dl) {
     char* imgData = (char*)dl;
@@ -32,7 +32,7 @@ extern "C" void gSPVertex(Gfx* pkt, uintptr_t v, int n, int v0) {
 extern "C" void gSPInvalidateTexCache(Gfx* pkt, uintptr_t texAddr) {
     char* imgData = (char*)texAddr;
 
-    if (texAddr != 0 && GameEngine_OTRSigCheck(imgData)) {
+    if (texAddr != 0 && GameEngine_OTRSigCheck(imgData) == 1) {
         auto res = Ship::Context::GetInstance()->GetResourceManager()->LoadResource(imgData);
 
         if (res->GetInitData()->Type == (uint32_t) Fast::ResourceType::DisplayList)