diff --git a/src/Plugin/Patches.php b/src/Plugin/Patches.php
index f636403e..2daba2c5 100644
--- a/src/Plugin/Patches.php
+++ b/src/Plugin/Patches.php
@@ -413,42 +413,13 @@ protected function getAndApplyPatch(RemoteFilesystem $downloader, $install_path,
             $downloader->copy($hostname, $patch_url, $filename, false);
         }
 
-        // Modified from drush6:make.project.inc
-        $patched = false;
         // The order here is intentional. p1 is most likely to apply with git apply.
         // p0 is next likely. p2 is extremely unlikely, but for some special cases,
         // it might be useful. p4 is useful for Magento 2 patches
         $patch_levels = $this->getConfig('patch-levels');
-        foreach ($patch_levels as $patch_level) {
-            if ($this->io->isVerbose()) {
-                $comment = 'Testing ability to patch with git apply.';
-                $comment .= ' This command may produce errors that can be safely ignored.';
-                $this->io->write('<comment>' . $comment . '</comment>');
-            }
-            $checked = $this->executeCommand(
-                'git -C %s apply --check -v %s %s',
-                $install_path,
-                $patch_level,
-                $filename
-            );
-            $output = $this->executor->getErrorOutput();
-            if (substr($output, 0, 7) == 'Skipped') {
-                // Git will indicate success but silently skip patches in some scenarios.
-                //
-                // @see https://github.com/cweagans/composer-patches/pull/165
-                $checked = false;
-            }
-            if ($checked) {
-                // Apply the first successful style.
-                $patched = $this->executeCommand(
-                    'git -C %s apply %s %s',
-                    $install_path,
-                    $patch_level,
-                    $filename
-                );
-                break;
-            }
-        }
+
+        // Attempt to apply with git apply
+        $patched = $this->applyPatchWithGit($install_path, $patch_levels, $filename);
 
         // In some rare cases, git will fail to apply a patch, fallback to using
         // the 'patch' command.
@@ -500,6 +471,58 @@ protected function isPatchingEnabled()
         return $enabled;
     }
 
+    /**
+     * Attempts to apply a patch with git apply
+     *
+     * @param $install_path
+     * @param $patch_levels
+     * @param $filename
+     *
+     * @return bool
+     *   TRUE if patch was applied, FALSE otherwise.
+     */
+    protected function applyPatchWithGit($install_path, $patch_levels, $filename)
+    {
+        // Do not use git apply unless the install path is itself a git repo
+        // @see https://stackoverflow.com/a/27283285
+        if (!is_dir($install_path . '/.git')) {
+            return false;
+        }
+
+        $patched = false;
+        foreach ($patch_levels as $patch_level) {
+            if ($this->io->isVerbose()) {
+                $comment = 'Testing ability to patch with git apply.';
+                $comment .= ' This command may produce errors that can be safely ignored.';
+                $this->io->write('<comment>' . $comment . '</comment>');
+            }
+            $checked = $this->executeCommand(
+                'git -C %s apply --check -v %s %s',
+                $install_path,
+                $patch_level,
+                $filename
+            );
+            $output = $this->executor->getErrorOutput();
+            if (substr($output, 0, 7) == 'Skipped') {
+                // Git will indicate success but silently skip patches in some scenarios.
+                //
+                // @see https://github.com/cweagans/composer-patches/pull/165
+                $checked = false;
+            }
+            if ($checked) {
+                // Apply the first successful style.
+                $patched = $this->executeCommand(
+                    'git -C %s apply %s %s',
+                    $install_path,
+                    $patch_level,
+                    $filename
+                );
+                break;
+            }
+        }
+        return $patched;
+    }
+
     /**
      * Executes a shell command with escaping.
      *