diff --git a/src/lib/file.cpp b/src/lib/file.cpp
index 5406d28..b0da8ab 100644
--- a/src/lib/file.cpp
+++ b/src/lib/file.cpp
@@ -61,10 +61,12 @@ ErrorOr<uint8_t> File::readByte(){
     uint8_t* nextPointer = new uint8_t;
     uint8_t nextByte;
     bool failure = false;
+    if (!this->size.isError && this->cursorPosition >= this->size.value) {
+        return ErrorOr<uint8_t>(true, ErrorCodes::OVERRUN);
+    }
     try {
         this->fileStream.seekg(this->cursorPosition);
 
-        //FIXME: check that a byte is available for read
         this->fileStream.read(reinterpret_cast<char*>(nextPointer), 1);
         nextByte = *nextPointer;
 
@@ -81,6 +83,9 @@ ErrorOr<std::vector<uint8_t>> File::read(uint64_t bytes){
     uint8_t* buffer = new uint8_t[bytes];
     std::vector<uint8_t> data;
     bool failure = false;
+    if (!this->size.isError && this->cursorPosition >= this->size.value+bytes) {
+        return ErrorOr<std::vector<uint8_t>>(true, ErrorCodes::OVERRUN);
+    }
     try {
         this->fileStream.seekg(this->cursorPosition);