diff --git a/codec-http2/pom.xml b/codec-http2/pom.xml
index c787a53c62..e9d74896ef 100644
--- a/codec-http2/pom.xml
+++ b/codec-http2/pom.xml
@@ -30,6 +30,8 @@
 
   <properties>
     <javaModuleName>io.netty.codec.http2</javaModuleName>
+    <!-- Needed for SSL tests as these use the SelfSignedCertificate -->
+    <argLine.java9.extras>--add-exports java.base/sun.security.x509=ALL-UNNAMED</argLine.java9.extras>
   </properties>
 
   <dependencies>
diff --git a/pom.xml b/pom.xml
index 1cb438dee7..0a9b73e486 100644
--- a/pom.xml
+++ b/pom.xml
@@ -216,6 +216,9 @@
         <jdk>15</jdk>
       </activation>
       <properties>
+        <argLine.java9.extras />
+        <!-- Export some stuff which is used during our tests -->
+        <argLine.java9>--illegal-access=deny ${argLine.java9.extras}</argLine.java9>
         <!-- Not use alpn agent as Java11+ supports alpn out of the box -->
         <argLine.alpnAgent />
         <forbiddenapis.skip>true</forbiddenapis.skip>
@@ -237,6 +240,9 @@
         <jdk>14</jdk>
       </activation>
       <properties>
+        <argLine.java9.extras />
+        <!-- Export some stuff which is used during our tests -->
+        <argLine.java9>--illegal-access=deny ${argLine.java9.extras}</argLine.java9>
         <!-- Not use alpn agent as Java11+ supports alpn out of the box -->
         <argLine.alpnAgent />
         <forbiddenapis.skip>true</forbiddenapis.skip>
@@ -255,6 +261,9 @@
         <jdk>13</jdk>
       </activation>
       <properties>
+        <argLine.java9.extras />
+        <!-- Export some stuff which is used during our tests -->
+        <argLine.java9>--illegal-access=deny ${argLine.java9.extras}</argLine.java9>
         <!-- Not use alpn agent as Java11+ supports alpn out of the box -->
         <argLine.alpnAgent />
         <forbiddenapis.skip>true</forbiddenapis.skip>