diff --git a/build.clj b/build.clj
index 90919c4..7d00c55 100644
--- a/build.clj
+++ b/build.clj
@@ -52,8 +52,8 @@
   (b/process {:command-args ["javac" "--enable-preview"
                              "src/java/coffi/ffi/Loader.java"
                              "-d" class-dir
-                             "-target" "21"
-                             "-source" "21"]})
+                             "-target" "22"
+                             "-source" "22"]})
   opts)
 
 (defn- write-pom
diff --git a/deps.edn b/deps.edn
index d0e1469..a6c2599 100644
--- a/deps.edn
+++ b/deps.edn
@@ -1,6 +1,6 @@
 {:paths ["src/clj" "target/classes" "resources"]
  :deps {org.clojure/clojure {:mvn/version "1.11.1"}
-        insn/insn {:mvn/version "0.2.1"}}
+        insn/insn {:mvn/version "0.5.4"}}
 
  :deps/prep-lib {:alias :build
                  :fn build/compile-java
diff --git a/src/clj/coffi/ffi.clj b/src/clj/coffi/ffi.clj
index bff4e99..365fa10 100644
--- a/src/clj/coffi/ffi.clj
+++ b/src/clj/coffi/ffi.clj
@@ -135,6 +135,7 @@
   method handle without reflection, unboxing primitives when needed."
   [args ret]
   {:flags #{:public :final}
+   :version 8
     :super clojure.lang.AFunction
     :fields [{:name "downcall_handle"
               :type MethodHandle
@@ -291,7 +292,7 @@
 
                  ;; cast null pointers to something understood by panama
                  (#{::mem/pointer} type)
-                 `(or ~sym (MemoryAddress/NULL))
+                 `(or ~sym (MemorySegment/NULL))
 
                  (mem/primitive-type type)
                  `(mem/serialize* ~sym ~type-sym ~session)
@@ -466,6 +467,7 @@
   boxes any primitives passed to it and calls a closed over [[IFn]]."
   [arg-types ret-type]
   {:flags #{:public :final}
+   :version 8
    :fields [{:name "upcall_ifn"
              :type IFn
              :flags #{:final}}]
@@ -538,7 +540,6 @@
 
 (defmethod mem/serialize* ::fn
   [f [_fn arg-types ret-type & {:keys [raw-fn?]}] arena]
-  (println "Attempting to serialize function of type" (str ret-type "(*)(" (clojure.string/join "," arg-types) ")"))
   (.upcallStub
    (Linker/nativeLinker)
    ^MethodHandle (cond-> f
diff --git a/src/clj/coffi/mem.clj b/src/clj/coffi/mem.clj
index fab0981..23139c1 100644
--- a/src/clj/coffi/mem.clj
+++ b/src/clj/coffi/mem.clj
@@ -269,14 +269,12 @@
   (.addCloseAction session action)
   nil)
 
-;; TODO(Joshua): Determine if this needs to exist at all
-#_
 (defn as-segment
   "Dereferences an `address` into a memory segment associated with the `session`."
-  (^MemorySegment [^MemoryAddress address size]
-   (MemorySegment/ofAddress address (long size) (connected-session)))
-  (^MemorySegment [^MemoryAddress address size session]
-   (MemorySegment/ofAddress address (long size) session)))
+  (^MemorySegment [^MemorySegment address size]
+   (.reinterpret (MemorySegment/ofAddress address) (long size) (connected-session) nil))
+  (^MemorySegment [^MemorySegment address size session]
+   (.reinterpret (MemorySegment/ofAddress address) (long size) session nil)))
 
 (defn copy-segment
   "Copies the content to `dest` from `src`.
@@ -1247,15 +1245,15 @@
   ::pointer)
 
 (defmethod serialize* ::c-string
-  [obj _type session]
+  [obj _type ^Arena session]
   (if obj
-    (address-of (.allocateUtf8String (arena-allocator session) ^String obj))
+    (.allocateFrom session ^String obj)
     (MemorySegment/NULL)))
 
 (defmethod deserialize* ::c-string
   [addr _type]
   (when-not (null? addr)
-    (.getUtf8String (.reinterpret ^MemorySegment addr Integer/MAX_VALUE) 0)))
+    (.getString (.reinterpret ^MemorySegment addr Integer/MAX_VALUE) 0)))
 
 ;;; Union types
 
diff --git a/test/c/ffi_test.c b/test/c/ffi_test.c
index c689e87..e38ff30 100644
--- a/test/c/ffi_test.c
+++ b/test/c/ffi_test.c
@@ -26,40 +26,55 @@ CString upcall_test(StringFactory fun) {
     return fun();
 }
 
+int upcall_test2(int (*f)(void)) {
+    return f();
+}
+
 int counter = 0;
 
 static char* responses[] = { "Hello, world!", "Goodbye friend.", "co'oi prenu" };
 
+char* upcall_test_int_fn_string_ret(int (*f)(void)) {
+    return responses[f()];
+}
+
 CString get_string1(void) {
-    return responses[counter++ % 3];
+  return responses[counter++ % 3];
 }
 
 CString get_string2(void) {
-    return "Alternate string";
+  return "Alternate string";
 }
 
 StringFactory get_downcall(int whichString) {
-    switch (whichString % 2) {
-    case 0:
-        return get_string1;
-    case 1:
-        return get_string2;
-    default:
-        return 0;
-    }
+  switch (whichString % 2) {
+  case 0:
+    return get_string1;
+  case 1:
+    return get_string2;
+  default:
+    return 0;
+  }
 }
 
 typedef struct alignment_test {
-    char a;
-    double x;
-    float y;
+  char a;
+  double x;
+  float y;
 } AlignmentTest;
 
 AlignmentTest get_struct() {
-    AlignmentTest ret = {};
-    ret.a = 'x';
-    ret.x = 3.14;
-    ret.y = 42.0;
+  AlignmentTest ret = {};
+  ret.a = 'x';
+  ret.x = 3.14;
+  ret.y = 42.0;
 
-    return ret;
+  return ret;
 }
+
+void test_call_with_trailing_string_arg(int a, int b, char* text) {
+  printf("call of `test_call_with_trailing_string_arg` with a=%i b=%i text='%s'",1,2,text);
+  printf("\r                                                                          ");
+  return;
+}
+
diff --git a/test/clj/coffi/ffi_test.clj b/test/clj/coffi/ffi_test.clj
index 15cc4b6..d45e3ae 100644
--- a/test/clj/coffi/ffi_test.clj
+++ b/test/clj/coffi/ffi_test.clj
@@ -29,8 +29,18 @@
 
 (t/deftest can-make-upcall
   (t/is (= ((ffi/cfn "upcall_test" [[::ffi/fn [] ::mem/c-string]] ::mem/c-string)
-            (fn [] "hello"))
-           "hello")))
+            (fn [] "hello from clojure from c from clojure"))
+           "hello from clojure from c from clojure")))
+
+(t/deftest can-make-upcall2
+  (t/is (= ((ffi/cfn "upcall_test2" [[::ffi/fn [] ::mem/int]] ::mem/int)
+            (fn [] 5))
+           5)))
+
+(t/deftest can-make-upcall-int-fn-string-ret
+  (t/is (= ((ffi/cfn "upcall_test_int_fn_string_ret" [[::ffi/fn [] ::mem/int]] ::mem/c-string)
+            (fn [] 2))
+           "co'oi prenu")))
 
 (mem/defalias ::alignment-test
   (layout/with-c-layout
@@ -49,3 +59,12 @@
   (ffi/freset! (ffi/static-variable "counter" ::mem/int) 1)
   (t/is (= ((ffi/cfn "get_string1" [] ::mem/c-string))
            "Goodbye friend.")))
+
+(t/deftest can-call-with-trailing-string-arg
+  (t/is
+   (=
+    ((ffi/cfn "test_call_with_trailing_string_arg"
+              [::mem/int ::mem/int ::mem/c-string]
+              ::mem/void)
+     1 2 "third arg"))))
+
diff --git a/test/clj/coffi/mem_test.clj b/test/clj/coffi/mem_test.clj
new file mode 100644
index 0000000..b52c1eb
--- /dev/null
+++ b/test/clj/coffi/mem_test.clj
@@ -0,0 +1,32 @@
+(ns coffi.mem-test
+  (:require
+   [clojure.test :as t]
+   [coffi.ffi :as ffi]
+   [coffi.layout :as layout]
+   [coffi.mem :as mem])
+  (:import
+   (java.lang.foreign
+    AddressLayout
+    Arena
+    MemoryLayout
+    MemorySegment
+    MemorySegment$Scope
+    SegmentAllocator
+    ValueLayout
+    ValueLayout$OfByte
+    ValueLayout$OfShort
+    ValueLayout$OfInt
+    ValueLayout$OfLong
+    ValueLayout$OfChar
+    ValueLayout$OfFloat
+    ValueLayout$OfDouble)
+   (java.lang.ref Cleaner)
+   (java.nio ByteOrder)))
+
+(ffi/load-library "target/ffi_test.so")
+
+(t/deftest can-serialize-string
+  (t/is
+   (instance? MemorySegment (mem/serialize "this is a string" ::mem/c-string))))
+
+