diff --git a/src/spellfile.c b/src/spellfile.c
index 6aeac86..d5ec3fe 100644
--- a/src/spellfile.c
+++ b/src/spellfile.c
@@ -816,7 +816,7 @@
 
     // read the length bytes, MSB first
     for (i = 0; i < cnt_bytes; ++i)
-	cnt = (cnt << 8) + getc(fd);
+	cnt = (cnt << 8) + (unsigned)getc(fd);
     if (cnt < 0)
     {
 	*cntp = SP_TRUNCERROR;