diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1687eedf1..02c9d5693 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,17 @@
 
 ## uefi - [Unreleased]
 
+### Added
+
+- Added EFI revision constants to `Revision`.
+
+### Fixed
+
+- The `BootServices::create_event_ex` and
+  `RuntimeServices::query_variable_info` methods now check the table
+  version to make sure it's 2.0 or higher before calling the associated
+  function pointers. This prevents potential invalid pointer access.
+
 ## uefi-macros - [Unreleased]
 
 ## uefi-services - [Unreleased]
@@ -32,6 +43,7 @@
 - `DevicePath` is now a DST that represents an entire device path. The
   `DevicePathInstance` and `DevicePathNode` provide views of path
   instances and nodes, respectively.
+- The methods of `Revision` are now `const`.
 
 ### Fixed
 
diff --git a/src/table/boot.rs b/src/table/boot.rs
index f0ecd5f2c..2307d9551 100644
--- a/src/table/boot.rs
+++ b/src/table/boot.rs
@@ -1,6 +1,6 @@
 //! UEFI services available during boot.
 
-use super::Header;
+use super::{Header, Revision};
 use crate::data_types::Align;
 use crate::proto::device_path::{DevicePath, FfiDevicePath};
 #[cfg(feature = "exts")]
@@ -437,6 +437,9 @@ impl BootServices {
     /// More than one event of type `EventType::TIMER` may be part of a single event group. However,
     /// there is no mechanism for determining which of the timers was signaled.
     ///
+    /// This operation is only supported starting with UEFI 2.0; earlier
+    /// versions will fail with [`Status::UNSUPPORTED`].
+    ///
     /// # Safety
     ///
     /// The caller must ensure they are passing a valid `Guid` as `event_group`, if applicable.
@@ -448,6 +451,10 @@ impl BootServices {
         notify_ctx: Option<NonNull<c_void>>,
         event_group: Option<NonNull<Guid>>,
     ) -> Result<Event> {
+        if self.header.revision < Revision::EFI_2_00 {
+            return Err(Status::UNSUPPORTED.into());
+        }
+
         let mut event = MaybeUninit::<Event>::uninit();
 
         (self.create_event_ex)(
diff --git a/src/table/revision.rs b/src/table/revision.rs
index ef2577f9e..c79810936 100644
--- a/src/table/revision.rs
+++ b/src/table/revision.rs
@@ -9,21 +9,41 @@ use core::fmt;
 #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
 pub struct Revision(u32);
 
+// Allow missing docs, there's nothing useful to document about these
+// constants.
+#[allow(missing_docs)]
+impl Revision {
+    pub const EFI_1_02: Self = Self::new(1, 2);
+    pub const EFI_1_10: Self = Self::new(1, 10);
+    pub const EFI_2_00: Self = Self::new(2, 00);
+    pub const EFI_2_10: Self = Self::new(2, 10);
+    pub const EFI_2_20: Self = Self::new(2, 20);
+    pub const EFI_2_30: Self = Self::new(2, 30);
+    pub const EFI_2_31: Self = Self::new(2, 31);
+    pub const EFI_2_40: Self = Self::new(2, 40);
+    pub const EFI_2_50: Self = Self::new(2, 50);
+    pub const EFI_2_60: Self = Self::new(2, 60);
+    pub const EFI_2_70: Self = Self::new(2, 70);
+    pub const EFI_2_80: Self = Self::new(2, 80);
+    pub const EFI_2_90: Self = Self::new(2, 90);
+}
+
 impl Revision {
     /// Creates a new revision.
-    pub fn new(major: u16, minor: u16) -> Self {
-        let (major, minor) = (u32::from(major), u32::from(minor));
+    pub const fn new(major: u16, minor: u16) -> Self {
+        let major = major as u32;
+        let minor = minor as u32;
         let value = (major << 16) | minor;
         Revision(value)
     }
 
     /// Returns the major revision.
-    pub fn major(self) -> u16 {
+    pub const fn major(self) -> u16 {
         (self.0 >> 16) as u16
     }
 
     /// Returns the minor revision.
-    pub fn minor(self) -> u16 {
+    pub const fn minor(self) -> u16 {
         self.0 as u16
     }
 }
@@ -35,3 +55,18 @@ impl fmt::Debug for Revision {
         write!(f, "{}.{}.{}", major, minor / 10, minor % 10)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_revision() {
+        let rev = Revision::EFI_2_31;
+        assert_eq!(rev.major(), 2);
+        assert_eq!(rev.minor(), 31);
+        assert_eq!(rev.0, 0x0002_001f);
+
+        assert!(Revision::EFI_1_10 < Revision::EFI_2_00);
+    }
+}
diff --git a/src/table/runtime.rs b/src/table/runtime.rs
index ef20eed15..6aa9087bf 100644
--- a/src/table/runtime.rs
+++ b/src/table/runtime.rs
@@ -1,6 +1,6 @@
 //! UEFI services available at runtime, even after the OS boots.
 
-use super::Header;
+use super::{Header, Revision};
 #[cfg(feature = "exts")]
 use crate::data_types::FromSliceWithNulError;
 use crate::result::Error;
@@ -248,11 +248,18 @@ impl RuntimeServices {
     /// Get information about UEFI variable storage space for the type
     /// of variable specified in `attributes`.
     ///
+    /// This operation is only supported starting with UEFI 2.0; earlier
+    /// versions will fail with [`Status::UNSUPPORTED`].
+    ///
     /// See [`VariableStorageInfo`] for details of the information returned.
     pub fn query_variable_info(
         &self,
         attributes: VariableAttributes,
     ) -> Result<VariableStorageInfo> {
+        if self.header.revision < Revision::EFI_2_00 {
+            return Err(Status::UNSUPPORTED.into());
+        }
+
         let mut info = VariableStorageInfo::default();
         unsafe {
             (self.query_variable_info)(