3 files changed, 3 insertions, 3 deletions
diff --git a/src/long_mode/mod.rs b/src/long_mode/mod.rs
index 866eb8f..7e8dff7 100644
--- a/src/long_mode/mod.rs
+++ b/src/long_mode/mod.rs
@@ -232,7 +232,7 @@ impl RegSpec {
     /// construct a `RegSpec` for non-rex byte reg `num`
     #[inline]
     pub fn rb(num: u8) -> RegSpec {
-        if num >= 18 {
+        if num >= 16 {
             panic!("invalid x86 rex-byte reg {}", num);
         }
 
diff --git a/src/protected_mode/mod.rs b/src/protected_mode/mod.rs
index 232284d..9c03faf 100644
--- a/src/protected_mode/mod.rs
+++ b/src/protected_mode/mod.rs
@@ -179,7 +179,7 @@ impl RegSpec {
     /// construct a `RegSpec` for mask reg `num`
     #[inline]
     pub fn mask(num: u8) -> RegSpec {
-        if num >= 32 {
+        if num >= 8 {
             panic!("invalid x86 mask reg {}", num);
         }
 
diff --git a/src/real_mode/mod.rs b/src/real_mode/mod.rs
index 92c0592..74e1c37 100644
--- a/src/real_mode/mod.rs
+++ b/src/real_mode/mod.rs
@@ -179,7 +179,7 @@ impl RegSpec {
     /// construct a `RegSpec` for mask reg `num`
     #[inline]
     pub fn mask(num: u8) -> RegSpec {
-        if num >= 32 {
+        if num >= 8 {
             panic!("invalid x86 mask reg {}", num);
         }