diff --git a/src/port.c b/src/port.c
index 3a48c940..b943a066 100644
--- a/src/port.c
+++ b/src/port.c
@@ -165,6 +165,13 @@ pic_fread(void *ptr, size_t block, size_t nitems, pic_file *file)
 
   size = block * nitems;        /* TODO: optimize block read */
 
+  /* take care of ungetc buf */
+  while (file->ur > 0) {
+    *dst++ = file->ub[--file->ur];
+    if (size == 0)
+      return block * nitems;
+  }
+
   while (1) {
     avail = file->c - file->s;
     if (size <= avail) {
@@ -221,6 +228,12 @@ pic_fgetc(pic_file *file)
   return buf[0];
 }
 
+int
+pic_ungetc(int c, pic_file *file)
+{
+  return file->ub[file->ur++] = (char)c;
+}
+
 int
 pic_fputc(int c, pic_file *file)
 {