diff --git a/src/manager.S b/src/manager.S
index 5eb6b19..f44baa0 100644
--- a/src/manager.S
+++ b/src/manager.S
@@ -103,44 +103,62 @@ init_compartments:
 /**
  * Function to add information for a compartment
  *
- * @param c1 Start address
- * @param c2 Size of memory region
- * @param c3 Function address
+ * @param x0 Compartment memory size
+ * @param x1 Compartment executable function
+ *
+ * @return Pointer to newly allocated memory region
  */
 .type add_compartment, "function"
 add_compartment:
+    // Store inputs and `lr` so we can call `mmap`
+    stp       x0, x1, [sp, #-32]!
+    str       lr, [sp, #16]
+    mov       x1, x0
+
+    // Allocate memory for new compartment
+    mov       x0, xzr    // address
+                         // length - already stored in `x1`
+    mov       w2, #3     // prot == PROT_READ | PROT_WRITE
+    mov       w3, #4098  // flags == MAP_PRIVATE | MAP_ANONYMOUS
+    mov       w4, #-1    // fd
+    mov       w5, wzr    // offset
+    bl        mmap
+
+    // Restore memory size and function address
+    ldp       x1, x2, [sp], #32
+    ldr       lr, [sp, #-16]
 
-  // Derive compartment PCC
-  cvtp        c3, x3
-  mov         x4, #320 // TODO dynamic value
-  scbndse     c3, c3, x4
-
-  // Derive compartment DDC
-  cvtp        c1, x1
-  scbnds      c2, c1, x2
-
-  // Store new PCC and DDC
-  ldr         x0, comps_addr
-  ldr         x1, comps_cnt
-  mov         x3, #COMP_SIZE
-  madd        x0, x1, x2, x0
-  stp         c3, c2, [x0]
-
-  // Increment counter
-  adr         x3, comps_cnt
-  ldr         x4, [x3]
-  add         x4, x4, #1
-  str         x4, [x3]
-
-  // Update switcher DDC
-  adr         x2, switcher_caps
-  ldr         c0, [x2]
-  gclen       x1, c0
-  add         x1, x1, #32
-  scbndse     c0, c0, x1
-  str         c0, [x2]
-
-  ret
+    // Derive compartment DDC
+    cvtp      c0, x0
+    scbnds    c0, c0, x1
+
+    // Derive compartment PCC
+    cvtp      c1, x2
+    mov       x2, #320 // TODO dynamic value
+    scbndse   c1, c1, x2
+
+    // Store new PCC and DDC
+    ldr       x2, comps_addr
+    ldr       x3, comps_cnt
+    mov       x4, #COMP_SIZE
+    madd      x2, x3, x4, x2
+    stp       c0, c1, [x2]
+
+    // Increment counter
+    adr       x3, comps_cnt
+    ldr       x4, [x3]
+    add       x4, x4, #1
+    str       x4, [x3]
+
+    // Update switcher DDC
+    //adr       x2, switcher_caps
+    //ldr       c0, [x2]
+    //gclen     x1, c0
+    //add       x1, x1, #32
+    //scbndse   c0, c0, x1
+    //str       c0, [x2]
+
+    ret
 
 /**
  * Function to delete an existing compartment data
diff --git a/tests/simple_add.c b/tests/simple_add.c
index 83118b6..82d0044 100644
--- a/tests/simple_add.c
+++ b/tests/simple_add.c
@@ -1,6 +1,7 @@
-#include "assert.h"
-#include "stdint.h"
-#include "stdlib.h"
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/mman.h>
 
 #include "cheriintrin.h"
 
@@ -10,24 +11,15 @@ static_assert(COMP_SIZE == sizeof(void* __capability) * 3, "Invalid `COMP_SIZE`
 static_assert(COMP_OFFSET_DDC == sizeof(void* __capability) * 1, "Invalid `COMP_OFFSET_DDC` provided.");
 static_assert(COMP_OFFSET_STK_ADDR == sizeof(void* __capability) * 2, "Invalid `COMP_OFFSET_STK_LEN` provided.");
 
-/*******************************************************************************
- * Globals and constants
- ******************************************************************************/
-
-const size_t max_comp_cnt = 2;
-const size_t switcher_mem_max_size = max_comp_cnt * COMP_SIZE;
-
 /*******************************************************************************
  * Extern functions
  ******************************************************************************/
 
-extern void asm_call_wrapper(void*, ...);
-extern void init_compartments(void*, size_t, void*);
-extern void add_compartment(void*, size_t, void*);
-extern int switch_compartment();
+extern void* __capability * comps_addr;
+extern size_t comps_cnt;
 
-extern void* comps_addr;
-extern void* switcher_caps;
+extern void* init_compartments();
+extern void* add_compartment(size_t, void*);
 
 /*******************************************************************************
  * Main
@@ -38,19 +30,20 @@ int comp_f_fn();
 int
 main()
 {
-    switcher_caps = malloc(sizeof(void* __capability) * 2);
-    comps_addr = malloc(COMP_SIZE * max_comp_cnt);
+    init_compartments();
+
+    size_t comp_size = 2000;
+    assert(add_compartment(comp_size, comp_f_fn) != MAP_FAILED);
 
-    void* switcher_start = malloc(switcher_mem_max_size);
-    void* switch_comp_addr = switch_compartment;
+    assert(comps_cnt == 1);
 
-    asm_call_wrapper(init_compartments,
-                     switcher_start, switcher_mem_max_size, switch_comp_addr);
+    void* __capability comp_ddc = comps_addr[0];
+    assert(cheri_is_valid(comp_ddc));
+    assert(cheri_length_get(comp_ddc) == comp_size);
 
-    const size_t comp_f_size = 1000;
-    uintptr_t comp_f_start = (uintptr_t) malloc(comp_f_size);
-    asm_call_wrapper(add_compartment,
-                     comp_f_start, comp_f_size, comp_f_fn);
+    void* __capability comp_pcc = comps_addr[1];
+    assert(cheri_is_valid(comp_pcc));
+    assert(cheri_address_get(comp_pcc) == (unsigned long) comp_f_fn);
 
     return 0;
 }