diff --git a/bswap.h b/bswap.h
index 63b81cc..1dd357e 100644
--- a/bswap.h
+++ b/bswap.h
@@ -151,7 +151,7 @@
 {
     uint8_t *p1 = (uint8_t *)p;
 
-    p1[0] = v;
+    p1[0] = v & 0xff;
     p1[1] = v >> 8;
 }
 
@@ -159,7 +159,7 @@
 {
     uint8_t *p1 = (uint8_t *)p;
 
-    p1[0] = v;
+    p1[0] = v & 0xff;
     p1[1] = v >> 8;
     p1[2] = v >> 16;
     p1[3] = v >> 24;
@@ -188,7 +188,7 @@
     uint8_t *p1 = (uint8_t *)p;
 
     p1[0] = v >> 8;
-    p1[1] = v;
+    p1[1] = v & 0xff;
 }
 
 static inline void cpu_to_be32wu(uint32_t *p, uint32_t v)
@@ -198,7 +198,7 @@
     p1[0] = v >> 24;
     p1[1] = v >> 16;
     p1[2] = v >> 8;
-    p1[3] = v;
+    p1[3] = v & 0xff;
 }
 
 #endif
diff --git a/hw/ide.c b/hw/ide.c
index 6ad1d08..96bc176 100644
--- a/hw/ide.c
+++ b/hw/ide.c
@@ -1210,7 +1210,7 @@
 static inline void cpu_to_ube16(uint8_t *buf, int val)
 {
     buf[0] = val >> 8;
-    buf[1] = val;
+    buf[1] = val & 0xff;
 }
 
 static inline void cpu_to_ube32(uint8_t *buf, unsigned int val)
@@ -1218,7 +1218,7 @@
     buf[0] = val >> 24;
     buf[1] = val >> 16;
     buf[2] = val >> 8;
-    buf[3] = val;
+    buf[3] = val & 0xff;
 }
 
 static inline int ube16_to_cpu(const uint8_t *buf)
diff --git a/hw/vga.c b/hw/vga.c
index 98c2234..f20c6cc 100644
--- a/hw/vga.c
+++ b/hw/vga.c
@@ -38,33 +38,33 @@
 
 /* force some bits to zero */
 const uint8_t sr_mask[8] = {
-    (uint8_t)~0xfc,
-    (uint8_t)~0xc2,
-    (uint8_t)~0xf0,
-    (uint8_t)~0xc0,
-    (uint8_t)~0xf1,
-    (uint8_t)~0xff,
-    (uint8_t)~0xff,
-    (uint8_t)~0x00,
+    0x03,
+    0x3d,
+    0x0f,
+    0x3f,
+    0x0e,
+    0x00,
+    0x00,
+    0xff,
 };
 
 const uint8_t gr_mask[16] = {
-    (uint8_t)~0xf0, /* 0x00 */
-    (uint8_t)~0xf0, /* 0x01 */
-    (uint8_t)~0xf0, /* 0x02 */
-    (uint8_t)~0xe0, /* 0x03 */
-    (uint8_t)~0xfc, /* 0x04 */
-    (uint8_t)~0x84, /* 0x05 */
-    (uint8_t)~0xf0, /* 0x06 */
-    (uint8_t)~0xf0, /* 0x07 */
-    (uint8_t)~0x00, /* 0x08 */
-    (uint8_t)~0xff, /* 0x09 */
-    (uint8_t)~0xff, /* 0x0a */
-    (uint8_t)~0xff, /* 0x0b */
-    (uint8_t)~0xff, /* 0x0c */
-    (uint8_t)~0xff, /* 0x0d */
-    (uint8_t)~0xff, /* 0x0e */
-    (uint8_t)~0xff, /* 0x0f */
+    0x0f, /* 0x00 */
+    0x0f, /* 0x01 */
+    0x0f, /* 0x02 */
+    0x1f, /* 0x03 */
+    0x03, /* 0x04 */
+    0x7b, /* 0x05 */
+    0x0f, /* 0x06 */
+    0x0f, /* 0x07 */
+    0xff, /* 0x08 */
+    0x00, /* 0x09 */
+    0x00, /* 0x0a */
+    0x00, /* 0x0b */
+    0x00, /* 0x0c */
+    0x00, /* 0x0d */
+    0x00, /* 0x0e */
+    0x00, /* 0x0f */
 };
 
 #define cbswap_32(__x) \
diff --git a/tcg/x86_64/tcg-target.c b/tcg/x86_64/tcg-target.c
index ce58fa1..33327d1 100644
--- a/tcg/x86_64/tcg-target.c
+++ b/tcg/x86_64/tcg-target.c
@@ -243,7 +243,7 @@
     }
     if (opc & P_EXT)
         tcg_out8(s, 0x0f);
-    tcg_out8(s, opc);
+    tcg_out8(s, opc & 0xff);
 }
 
 static inline void tcg_out_modrm(TCGContext *s, int opc, int r, int rm)