diff --git a/rustls-libssl/src/conf.rs b/rustls-libssl/src/conf.rs
index cac89c0..6b4893b 100644
--- a/rustls-libssl/src/conf.rs
+++ b/rustls-libssl/src/conf.rs
@@ -6,7 +6,7 @@ use rustls::ProtocolVersion;
 
 use crate::error::Error;
 use crate::not_thread_safe::NotThreadSafe;
-use crate::{Ssl, SslContext};
+use crate::{Ssl, SslContext, VerifyMode};
 
 #[derive(Default)]
 pub(super) struct SslConfigCtx {
@@ -123,6 +123,57 @@ impl SslConfigCtx {
         })
     }
 
+    fn verify_mode(&mut self, raw_mode: Option<&str>) -> Result<ActionResult, Error> {
+        // If there's a SSL_CTX or SSL set then we want to mutate the existing verify_mode.
+        let mut verify_mode = match &self.state {
+            State::Validating => VerifyMode::default(),
+            State::ApplyingToSsl(ssl) => ssl.get().verify_mode,
+            State::ApplyingToCtx(ctx) => ctx.get().verify_mode,
+        };
+
+        let raw_mode = match raw_mode {
+            Some(raw_mode) => raw_mode,
+            None => return Ok(ActionResult::ValueRequired),
+        };
+
+        if !self.flags.is_server() && !self.flags.is_client() {
+            return Err(Error::bad_data("neither a client or a server"));
+        }
+
+        // "The value argument is a comma separated list of flags to set."
+        let mode_parts = raw_mode.split(',').collect::<Vec<&str>>();
+        for part in mode_parts {
+            match (part, self.flags.is_server()) {
+                // "Peer enables peer verification: for clients only."
+                ("Peer", false) => verify_mode.0 |= VerifyMode::PEER,
+                // "Request requests but does not require a certificate from the client.  Servers only."
+                ("Request", true) => verify_mode.0 |= VerifyMode::PEER,
+                // "Require requests and requires a certificate from the client: an error occurs if the
+                // client does not present a certificate. Servers only."
+                ("Require", true) => {
+                    verify_mode.0 |= VerifyMode::PEER | VerifyMode::FAIL_IF_NO_PEER_CERT
+                }
+                // We do not implement Once, RequestPostHandshake and RequiresPostHandshake,
+                // but don't error if provided.
+                ("Once" | "RequestPostHandshake" | "RequirePostHandshake", _) => {}
+                _ => return Err(Error::bad_data("unrecognized verify mode")),
+            }
+        }
+
+        Ok(match &self.state {
+            // OpenSSL returns "2" for this case...
+            State::Validating => ActionResult::Applied,
+            State::ApplyingToCtx(ctx) => {
+                ctx.get_mut().set_verify(verify_mode);
+                ActionResult::Applied
+            }
+            State::ApplyingToSsl(ssl) => {
+                ssl.get_mut().set_verify(verify_mode);
+                ActionResult::Applied
+            }
+        })
+    }
+
     fn parse_protocol_version(proto: Option<&str>) -> Option<u16> {
         Some(match proto {
             Some("None") => 0,
@@ -256,6 +307,8 @@ type CommandAction = fn(&mut SslConfigCtx, value: Option<&str>) -> Result<Action
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[repr(i32)]
 enum ActionResult {
+    /// The action required a value but was provided NULL.
+    ValueRequired = -3,
     /// The action value was recognized, but not applied.
     ///
     /// For example, if no `SSL_CTX` has been set a [`CommandAction`] may return `NotApplied` after
@@ -340,4 +393,11 @@ const SUPPORTED_COMMANDS: &[Command] = &[
         value_type: ValueType::String,
         action: SslConfigCtx::max_protocol,
     },
+    Command {
+        name_file: Some("VerifyMode"),
+        name_cmdline: None,
+        flags: Flags(Flags::ANY),
+        value_type: ValueType::String,
+        action: SslConfigCtx::verify_mode,
+    },
 ];
diff --git a/rustls-libssl/tests/config.c b/rustls-libssl/tests/config.c
index a8108e4..b5c4863 100644
--- a/rustls-libssl/tests/config.c
+++ b/rustls-libssl/tests/config.c
@@ -20,6 +20,8 @@ static const char *supported_cmds[] = {
 
     "-max_protocol", CUSTOM_PREFIX "max_protocol",
     "MaxProtocol",   CUSTOM_PREFIX "MaxProtocol",
+
+    "VerifyMode",    CUSTOM_PREFIX "VerifyMode",
 };
 
 #define NUM_SUPPORTED_CMDS (sizeof(supported_cmds) / sizeof(supported_cmds[0]))
@@ -148,6 +150,86 @@ void test_min_max_versions(void) {
   SSL_free(ssl);
 }
 
+static const char *verify_modes[] = {
+    NULL,   "",        "Ludicrous", "Ludicrous,Absurd",
+    "Peer", "Request", "Require",   "Request,Require",
+};
+
+#define NUM_VERIFY_MODES (sizeof(verify_modes) / sizeof(verify_modes[0]))
+
+void set_verify_modes(SSL_CONF_CTX *cctx, SSL_CTX *ctx, SSL *ssl) {
+  for (unsigned long i = 0; i < NUM_VERIFY_MODES; i++) {
+    const char *mode = verify_modes[i];
+    int res = SSL_CONF_cmd(cctx, "VerifyMode", mode);
+    printf("\t\tcmd VerifyMode '%s' returns %d\n", mode == NULL ? "NULL" : mode,
+           res);
+    if (ctx != NULL) {
+      printf("\t\tSSL_CTX_get_verify_mode %d\n", SSL_CTX_get_verify_mode(ctx));
+    }
+    if (ssl != NULL) {
+      printf("\t\tSSL_get_verify_mode %d\n", SSL_get_verify_mode(ssl));
+    }
+  }
+}
+
+void test_verify_mode(void) {
+  SSL_CONF_CTX *cctx = SSL_CONF_CTX_new();
+  assert(cctx != NULL);
+
+  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_FILE);
+  printf("\tPre-ctx (not client or server):\n");
+  set_verify_modes(cctx, NULL, NULL);
+
+  printf("\tPre-ctx (client):\n");
+  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_CLIENT);
+  set_verify_modes(cctx, NULL, NULL);
+  SSL_CONF_CTX_clear_flags(cctx, SSL_CONF_FLAG_CLIENT);
+
+  printf("\tPre-ctx (server):\n");
+  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_SERVER);
+  set_verify_modes(cctx, NULL, NULL);
+  SSL_CONF_CTX_clear_flags(cctx, SSL_CONF_FLAG_SERVER);
+
+  SSL_CTX *ctx = SSL_CTX_new(TLS_method());
+  assert(ctx != NULL);
+  SSL_CONF_CTX_set_ssl_ctx(cctx, ctx);
+
+  printf("\tWith ctx (not client or server):\n");
+  set_verify_modes(cctx, ctx, NULL);
+
+  printf("\tWith ctx (client):\n");
+  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_CLIENT);
+  set_verify_modes(cctx, ctx, NULL);
+  SSL_CONF_CTX_clear_flags(cctx, SSL_CONF_FLAG_CLIENT);
+
+  printf("\tWith ctx (server):\n");
+  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_SERVER);
+  set_verify_modes(cctx, ctx, NULL);
+  SSL_CONF_CTX_clear_flags(cctx, SSL_CONF_FLAG_SERVER);
+
+  SSL *ssl = SSL_new(ctx);
+  assert(ssl != NULL);
+  SSL_CONF_CTX_set_ssl(cctx, ssl);
+
+  printf("\tWith ssl (not client or server):\n");
+  set_verify_modes(cctx, NULL, ssl);
+
+  printf("\tWith ssl (client):\n");
+  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_CLIENT);
+  set_verify_modes(cctx, NULL, ssl);
+  SSL_CONF_CTX_clear_flags(cctx, SSL_CONF_FLAG_CLIENT);
+
+  printf("\tWith ssl (server):\n");
+  SSL_CONF_CTX_set_flags(cctx, SSL_CONF_FLAG_SERVER);
+  set_verify_modes(cctx, NULL, ssl);
+  SSL_CONF_CTX_clear_flags(cctx, SSL_CONF_FLAG_SERVER);
+
+  assert(SSL_CONF_CTX_finish(cctx));
+  SSL_CONF_CTX_free(cctx);
+  SSL_CTX_free(ctx);
+  SSL_free(ssl);
+}
+
 int main(void) {
   printf("Supported commands:\n");
   printf("no base flags, default prefix:\n");
@@ -170,4 +252,7 @@ int main(void) {
 
   printf("Min/Max version:\n");
   test_min_max_versions();
+
+  printf("VerifyMode:\n");
+  test_verify_mode();
 }