diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8b2c0dc..e41410e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,7 +20,7 @@ find_package(ZLIB)
 find_package(BZip2)
 
 if (UNIX OR MINGW)
-    add_compile_options(-std=c99 -fomit-frame-pointer)
+    add_compile_options(-fomit-frame-pointer -D_FILE_OFFSET_BITS=64)
 endif (UNIX OR MINGW)
 
 #sources
diff --git a/common/stream.c b/common/stream.c
index 18c1ebf..242174a 100644
--- a/common/stream.c
+++ b/common/stream.c
@@ -61,10 +61,12 @@ static bool file_seek(void *data, off64_t offset, int origin)
 {
 #ifdef _MSC_VER
     return _fseeki64(data, offset, origin) == 0;
+#elif defined __unix__
+    return fseeko(data, offset, origin) == 0;
 #else
-    if (offset > INT32_MAX)
-        return false;
-    return fseek(data, (long)offset, origin) == 0;
+	if (offset > INT32_MAX)
+		return false;
+        return fseek(data, (long)offset, origin) == 0;
 #endif
 }
 
@@ -72,6 +74,8 @@ static off64_t file_tell(void *data)
 {
 #ifdef _MSC_VER
     return _ftelli64(data);
+#elif defined __unix__
+    return ftello(data);
 #else
     return ftell(data);
 #endif