diff --git a/code/FBXConverter.cpp b/code/FBXConverter.cpp
index d7a734852..8f221de4c 100644
--- a/code/FBXConverter.cpp
+++ b/code/FBXConverter.cpp
@@ -1108,7 +1108,7 @@ private:
 	{
 		// locate source materials for this mesh
 		const std::vector<const Material*>& mats = model.GetMaterials();
-		if (materialIndex >= mats.size() || materialIndex < 0) {
+		if (static_cast<unsigned int>(materialIndex) >= mats.size() || materialIndex < 0) {
 			FBXImporter::LogError("material index out of bounds, setting default material");
 			out->mMaterialIndex = GetDefaultMaterial();
 			return;
diff --git a/code/FBXParser.cpp b/code/FBXParser.cpp
index b79f5eb1a..8661e5531 100644
--- a/code/FBXParser.cpp
+++ b/code/FBXParser.cpp
@@ -311,7 +311,7 @@ size_t ParseTokenAsDim(const Token& t, const char*& err_out)
 		ai_assert(t.end() - data == 9);
 		BE_NCONST uint64_t id = *reinterpret_cast<const uint64_t*>(data+1);
 		AI_SWAP8(id);
-		return id;
+		return static_cast<size_t>(id);
 	}
 
 	if(*t.begin() != '*') {