diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4c603ee3..a9839652 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 - **Bug Fix** (Pro): The HTML Compressor was returning an empty string upon encountering an invalid UTF-8 sequence. See [Issue #871](https://github.com/websharks/comet-cache/issues/871) reported by a Comet Cache user.
 - **Compatibility** (Pro): Many improvements to the Pro software update system, including changes to the API Endpoints and the Proxy Fallback endpoint. See [Issue #879](https://github.com/websharks/comet-cache/issues/879) and [Issue #315](https://github.com/websharks/comet-cache-pro/pull/315) for full details.
 - **Compatibility**: Fixed a WooCommerce compatibility issue that was generating a "Notice: id was called incorrectly. Product properties should not be accessed directly." Props @vestaxpdx. See [Issue #896](https://github.com/websharks/comet-cache/issues/896).
+- **Bug Fix:** Corrected a bug in the pro upgrader that prevented beta releases from being installed whenever they were desired by a site owner. Even when a site owner explicitly enabled beta release updates, they were not coming through due to problematic calls to `version_compare()` against a version with a dev-state suffix. This same bug was causing some oddities in version-specific upgrade routines, and in upgrade routines in general whenever a beta release was installed on top of an existing formal release state; i.e., when existing, previous version did not have a dev-state suffix, which is typical. Fixed all in this release. See [Issue #909 comment](https://github.com/websharks/comet-cache/issues/909#issuecomment-321953490).
 
 = v170220 =
 
diff --git a/src/includes/classes/VsUpgrades.php b/src/includes/classes/VsUpgrades.php
index 9e3b7845..59ae8235 100644
--- a/src/includes/classes/VsUpgrades.php
+++ b/src/includes/classes/VsUpgrades.php
@@ -54,7 +54,7 @@ protected function runHandlers()
      */
     protected function fromLte150807()
     {
-        if (version_compare($this->prev_version, '150807', '<=')) {
+        if ($this->versionCompare($this->prev_version, '150807', '<=', true)) {
             delete_site_option(GLOBAL_NS.'_errors'); // No longer necessary.
 
             if (is_multisite() && is_array($child_blogs = $this->plugin->getBlogs())) {
@@ -92,7 +92,7 @@ protected function fromLte150807()
      */
     protected function fromLte151107()
     {
-        if (version_compare($this->prev_version, '151107', '<=')) {
+        if ($this->versionCompare($this->prev_version, '151107', '<=', true)) {
             if (is_array($existing_options = get_site_option(GLOBAL_NS.'_options'))) {
                 if (!empty($existing_options['cache_clear_xml_sitemap_patterns']) && mb_strpos($existing_options['cache_clear_xml_sitemap_patterns'], '**') === false) {
                     $this->plugin->options['cache_clear_xml_sitemap_patterns'] = str_replace('*', '**', $existing_options['cache_clear_xml_sitemap_patterns']);
@@ -131,7 +131,7 @@ protected function fromLte151107()
      */
     protected function fromLte151114()
     {
-        if (version_compare($this->prev_version, '151114', '<=')) {
+        if ($this->versionCompare($this->prev_version, '151114', '<=', true)) {
             if (!$this->plugin->isApache()) {
                 return; // Not running the Apache web server.
             }
@@ -214,7 +214,7 @@ protected function fromZenCache()
      */
     protected function fromLte160227()
     {
-        if (version_compare($this->prev_version, '160227', '<=')) {
+        if ($this->versionCompare($this->prev_version, '160227', '<=', true)) {
             if (is_array($existing_options = get_site_option(GLOBAL_NS.'_options'))) {
                 $this->plugin->options['cache_clear_term_other_enable'] = $this->plugin->default_options['cache_clear_term_other_enable'];
                 if ($this->plugin->options !== $existing_options) {
@@ -235,7 +235,7 @@ protected function fromLte160227()
      */
     protected function fromLte160521()
     {
-        if (version_compare($this->prev_version, '160521', '<=')) {
+        if ($this->versionCompare($this->prev_version, '160521', '<=', true)) {
             $this->plugin->dismissMainNotice('allow_url_fopen_disabled');
             $this->plugin->removeAdvancedCache();
 
@@ -264,7 +264,7 @@ protected function fromLte160521()
      */
     protected function fromLte160709()
     {
-        if (version_compare($this->prev_version, '160709', '<=')) {
+        if ($this->versionCompare($this->prev_version, '160709', '<=', true)) {
             $this->plugin->dismissMainNotice('new-pro-version-available'); // Dismiss any existing notices like this; upgrade notices are handled by WordPress now.
         }
     }
@@ -275,7 +275,7 @@ protected function fromLte160709()
      */
     protected function fromLte161108()
     {
-        if (version_compare($this->prev_version, '161108', '<=')) {
+        if ($this->versionCompare($this->prev_version, '161108', '<=', true)) {
             if (is_array($existing_options = get_site_option(GLOBAL_NS.'_options'))) {
                 if (IS_PRO && isset($existing_options['htmlc_css_exclusions']) && empty($existing_options['htmlc_css_exclusions'])) {
                     $this->plugin->options['htmlc_css_exclusions'] = $this->plugin->default_options['htmlc_css_exclusions'];
diff --git a/src/includes/traits/Plugin/InstallUtils.php b/src/includes/traits/Plugin/InstallUtils.php
index 832cebc2..296ebc05 100644
--- a/src/includes/traits/Plugin/InstallUtils.php
+++ b/src/includes/traits/Plugin/InstallUtils.php
@@ -53,7 +53,7 @@ public function checkVersion()
     {
         $prev_version = $this->options['version'];
 
-        if (version_compare($prev_version, VERSION, '>=')) {
+        if ($this->versionCompare($prev_version, VERSION, '>=', true)) {
             return; // Nothing to do; up-to-date.
         }
         $this->options = $this->getOptions(false, true);
diff --git a/src/includes/traits/Plugin/UpdateUtils.php b/src/includes/traits/Plugin/UpdateUtils.php
index 865b1c86..23362220 100644
--- a/src/includes/traits/Plugin/UpdateUtils.php
+++ b/src/includes/traits/Plugin/UpdateUtils.php
@@ -41,7 +41,7 @@ public function maybeCheckLatestProVersion()
         }
         if ($latest_pro_version && preg_match('/^[0-9]{6}/u', $latest_pro_version)) {
             $this->updateOptions(['latest_pro_version' => $latest_pro_version]);
-            if (version_compare($latest_pro_version, VERSION, '>')) {
+            if ($this->versionCompare($latest_pro_version, VERSION, '>', true)) {
                 $this->maybeCheckLatestProPackage();
             }
         }
@@ -155,7 +155,7 @@ public function onGetSiteTransientUpdatePlugins($report)
         $latest_version = $this->options['latest_pro_version'];
         $latest_package = $this->options['latest_pro_package'];
 
-        if ($latest_version && $latest_package && version_compare($latest_version, VERSION, '>')) {
+        if ($latest_version && $latest_package && $this->versionCompare($latest_version, VERSION, '>', true)) {
             $report->response[$plugin_basename] = (object) [
                 'id'          => 0,
                 'url'         => $plugin_url,
@@ -191,5 +191,35 @@ public function maybeAutoUpdateInBackground($update, $item)
             return $update; // Unchanged in this case.
         }
     }
+
+    /**
+     * Version compare.
+     *
+     * @since 17xxxx Version compare.
+     *
+     * @param string $one                   Version one.
+     * @param string $two                   Version two.
+     * @param string $operator              Comparison operator.
+     * @param bool   $maybe_strip_dev_state Maybe strip dev-state.
+     *
+     * @return bool True or false.
+     */
+    public function versionCompare($one, $two, $operator, $maybe_strip_dev_state = false)
+    {
+        $one      = (string) $one;
+        $two      = (string) $two;
+        $operator = (string) $operator;
+
+        // NOTE: Stripping dev-state suffix.
+        // The method must be called with `$maybe_strip_dev_state = true`,
+        // AND, the site owner must have explicitly enabled beta releases.
+
+        if ($maybe_strip_dev_state && !$this->options['pro_update_check_stable']) {
+            $regex = '/\-(?:dev|rc|alpha|beta|pl).*$/ui';
+            $one   = preg_replace($regex, '', $one);
+            $two   = preg_replace($regex, '', $two);
+        }
+        return (bool) version_compare($one, $two, $operator);
+    }
 }
 /*[/pro]*/