diff --git a/src/atmega8/zfconf.h b/src/atmega8/zfconf.h
index 605c990..33e105d 100644
--- a/src/atmega8/zfconf.h
+++ b/src/atmega8/zfconf.h
@@ -40,6 +40,9 @@ typedef int32_t zf_cell;
 #define ZF_CELL_FMT "%ld"
 #define ZF_SCAN_FMT "%ld"
 
+/* zf_int use for bitops, some arch int type width is less than register width,
+   it will cause sign fill, so we need manual specify it */
+typedef int zf_int;
 
 /* The type to use for pointers and adresses. 'unsigned int' is usually a good
  * choice for best performance and smallest code size */
diff --git a/src/linux/zfconf.h b/src/linux/zfconf.h
index 4a06fc0..6b7f1ea 100644
--- a/src/linux/zfconf.h
+++ b/src/linux/zfconf.h
@@ -40,6 +40,9 @@ typedef float zf_cell;
 #define ZF_CELL_FMT "%.14g"
 #define ZF_SCAN_FMT "%f"
 
+/* zf_int use for bitops, some arch int type width is less than register width,
+   it will cause sign fill, so we need manual specify it */
+typedef int zf_int;
 
 /* The type to use for pointers and adresses. 'unsigned int' is usually a good
  * choice for best performance and smallest code size */
diff --git a/src/zforth/zforth.c b/src/zforth/zforth.c
index 42e2b20..32456d6 100644
--- a/src/zforth/zforth.c
+++ b/src/zforth/zforth.c
@@ -727,25 +727,25 @@ static void do_prim(zf_prim op, const char *input)
 			break;
 		
 		case PRIM_AND:
-			zf_push((int)zf_pop() & (int)zf_pop());
+			zf_push((zf_int)zf_pop() & (zf_int)zf_pop());
 			break;
 
 		case PRIM_OR:
-			zf_push((int)zf_pop() | (int)zf_pop());
+			zf_push((zf_int)zf_pop() | (zf_int)zf_pop());
 			break;
 
 		case PRIM_XOR:
-			zf_push((int)zf_pop() ^ (int)zf_pop());
+			zf_push((zf_int)zf_pop() ^ (zf_int)zf_pop());
 			break;
 
 		case PRIM_SHL:
 			d1 = zf_pop();
-			zf_push((int)zf_pop() << (int)d1);
+			zf_push((zf_int)zf_pop() << (zf_int)d1);
 			break;
 
 		case PRIM_SHR:
 			d1 = zf_pop();
-			zf_push((int)zf_pop() >> (int)d1);
+			zf_push((zf_int)zf_pop() >> (zf_int)d1);
 			break;
 
 		default: