diff --git a/csharp/ql/src/Security Features/CWE-1004/CookieWithoutHttpOnly.ql b/csharp/ql/src/Security Features/CWE-1004/CookieWithoutHttpOnly.ql
index 4205fb4f70c..dcc520540bb 100644
--- a/csharp/ql/src/Security Features/CWE-1004/CookieWithoutHttpOnly.ql	
+++ b/csharp/ql/src/Security Features/CWE-1004/CookieWithoutHttpOnly.ql	
@@ -82,7 +82,8 @@ predicate nonHttpOnlyCookieCall(Call c) {
         or
         // IResponseCookies.Append(String, String) was called, `HttpOnly` is set to `false` by default
         mc = c and
-        mc.getNumberOfArguments() < 3
+        mc.getNumberOfArguments() < 3 and
+        mc.getTarget().getParameter(0).getType() instanceof StringType
       )
     )
     or
diff --git a/csharp/ql/src/Security Features/CWE-614/CookieWithoutSecure.ql b/csharp/ql/src/Security Features/CWE-614/CookieWithoutSecure.ql
index c52a5cd992b..2a90698ed27 100644
--- a/csharp/ql/src/Security Features/CWE-614/CookieWithoutSecure.ql	
+++ b/csharp/ql/src/Security Features/CWE-614/CookieWithoutSecure.ql	
@@ -57,7 +57,8 @@ predicate insecureCookieAppend(Expr sink) {
   exists(MethodCall mc, MicrosoftAspNetCoreHttpResponseCookies iResponse |
     mc = sink and
     iResponse.getAppendMethod() = mc.getTarget() and
-    mc.getNumberOfArguments() < 3
+    mc.getNumberOfArguments() < 3 and
+    mc.getTarget().getParameter(0).getType() instanceof StringType
   )
 }