diff --git a/devsmlc.h b/devsmlc.h
index 2c8de8e..abf35ef 100644
--- a/devsmlc.h
+++ b/devsmlc.h
@@ -250,7 +250,7 @@ int devsmlc (int class, int func, int device) {
   char *bp;
   char buf[SMLC_BUFSIZE];
   int bufidx;
-  char ch;
+  unsigned char ch;
   time_t currenttime;
   uint16_t data;
   ea_t dmcbufbegea;