diff --git a/src/liballoc/string.rs b/src/liballoc/string.rs
index c1ef1c2f96c7..02ecb65fa38f 100644
--- a/src/liballoc/string.rs
+++ b/src/liballoc/string.rs
@@ -2008,7 +2008,7 @@ impl From<Box<str>> for String {
     }
 }
 
-#[stable(feature = "box_from_str", since = "1.18.0")]
+#[stable(feature = "box_from_str", since = "1.20.0")]
 impl From<String> for Box<str> {
     fn from(s: String) -> Box<str> {
         s.into_boxed_str()
diff --git a/src/libstd/ffi/c_str.rs b/src/libstd/ffi/c_str.rs
index 1586e0a4ddbd..5f0b11a616eb 100644
--- a/src/libstd/ffi/c_str.rs
+++ b/src/libstd/ffi/c_str.rs
@@ -585,7 +585,7 @@ impl From<Box<CStr>> for CString {
     }
 }
 
-#[stable(feature = "box_from_c_string", since = "1.18.0")]
+#[stable(feature = "box_from_c_string", since = "1.20.0")]
 impl From<CString> for Box<CStr> {
     #[inline]
     fn from(s: CString) -> Box<CStr> {
diff --git a/src/libstd/ffi/os_str.rs b/src/libstd/ffi/os_str.rs
index 3815f9866818..3232a51546e7 100644
--- a/src/libstd/ffi/os_str.rs
+++ b/src/libstd/ffi/os_str.rs
@@ -542,7 +542,7 @@ impl From<Box<OsStr>> for OsString {
     }
 }
 
-#[stable(feature = "box_from_os_string", since = "1.18.0")]
+#[stable(feature = "box_from_os_string", since = "1.20.0")]
 impl From<OsString> for Box<OsStr> {
     fn from(s: OsString) -> Box<OsStr> {
         s.into_boxed_os_str()
diff --git a/src/libstd/path.rs b/src/libstd/path.rs
index e9bf7b33b8e4..7a8c89353940 100644
--- a/src/libstd/path.rs
+++ b/src/libstd/path.rs
@@ -1348,7 +1348,7 @@ impl From<Box<Path>> for PathBuf {
     }
 }
 
-#[stable(feature = "box_from_path_buf", since = "1.18.0")]
+#[stable(feature = "box_from_path_buf", since = "1.20.0")]
 impl From<PathBuf> for Box<Path> {
     fn from(p: PathBuf) -> Box<Path> {
         p.into_boxed_path()