diff --git a/src/CSPBuilder.php b/src/CSPBuilder.php
index 18aa112..b8821a8 100644
--- a/src/CSPBuilder.php
+++ b/src/CSPBuilder.php
@@ -149,7 +149,7 @@ public function compile(): string
             $compiled []= 'upgrade-insecure-requests';
         }
 
-        $this->compiled = implode('', $compiled);
+        $this->compiled = rtrim(implode('', $compiled), '; ');
         $this->needsCompile = false;
         return $this->compiled;
     }
diff --git a/test/BasicTest.php b/test/BasicTest.php
index 9f0ae31..8319db9 100644
--- a/test/BasicTest.php
+++ b/test/BasicTest.php
@@ -70,6 +70,23 @@ public function testBasicFromData()
         );
     }
 
+    /**
+     * @throws \Exception
+     */
+    public function testNoTrailingSemicolon()
+    {
+        $csp = (new CSPBuilder())
+            ->setSelfAllowed('default-src', true)
+            ->addSource('img-src', 'ytimg.com')
+            ->disableOldBrowserSupport()
+        ;
+
+        $this->assertEquals(
+            "default-src 'self'; img-src ytimg.com",
+            $csp->getCompiledHeader()
+        );
+    }
+
     /**
      * @throws \Exception
      */