diff --git a/src/llvm_backend_const.cpp b/src/llvm_backend_const.cpp
index 18b6ee6f6..bcf2905ba 100644
--- a/src/llvm_backend_const.cpp
+++ b/src/llvm_backend_const.cpp
@@ -99,7 +99,7 @@ LLVMValueRef llvm_const_cast(LLVMValueRef val, LLVMTypeRef dst) {
 		return LLVMConstNull(dst);
 	}
 
-	GB_ASSERT_MSG(LLVMSizeOf(dst) == LLVMSizeOf(src), "%s vs %s", LLVMPrintTypeToString(dst), LLVMPrintTypeToString(src));
+	GB_ASSERT_MSG(lb_sizeof(dst) == lb_sizeof(src), "%s vs %s", LLVMPrintTypeToString(dst), LLVMPrintTypeToString(src));
 	LLVMTypeKind kind = LLVMGetTypeKind(dst);
 	switch (kind) {
 	case LLVMPointerTypeKind: