diff --git a/include/mach_detours.h b/include/mach_detours.h
index 002e880..382a022 100644
--- a/include/mach_detours.h
+++ b/include/mach_detours.h
@@ -11,6 +11,7 @@
 typedef void* detour_func_t;
 
 #define	detour_err_in_progress	(err_local | 1)
+#define	detour_err_wrong_thread	(err_local | 2)
 
 mach_error_t detour_transaction_begin();
 mach_error_t detour_transaction_abort();
diff --git a/src/detours_internal.h b/src/detours_internal.h
index e3a734b..5d204e5 100644
--- a/src/detours_internal.h
+++ b/src/detours_internal.h
@@ -9,11 +9,19 @@
 #if DETOUR_DEBUG
 #define DETOUR_TRACE(x) printf x
 #define DETOUR_BREAK()  raise(SIGTRAP)
+#define DETOUR_CHECK(x) \
+    { \
+        kern_return_t check_error = (x); \
+        if (check_error != err_none) { \
+            DETOUR_BREAK(); \
+        } \
+    }
 #else
 #include <signal.h>
 #include <stdio.h>
 #define DETOUR_TRACE(x)
 #define DETOUR_BREAK()
+#define DETOUR_CHECK(x) (x)
 #endif
 #endif
 
diff --git a/src/mach_detours.c b/src/mach_detours.c
index 840deb1..d3f444e 100644
--- a/src/mach_detours.c
+++ b/src/mach_detours.c
@@ -8,8 +8,9 @@
 
 #include <stdatomic.h>
 #include <stdint.h>
+#include <stdlib.h>
 
-#include <mach/mach_init.h>
+#include <mach/mach.h>
 #include <mach/mach_vm.h>
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -53,6 +54,15 @@ static void internal_detour_runnable_trampoline_regions()
     }
 }
 
+static void internal_detour_free_trampoline(detour_trampoline* trampoline)
+{
+    detour_region* region = (detour_region*)((uintptr_t)trampoline & ~(uintptr_t)0xffff);
+
+    memset(trampoline, 0, sizeof(*trampoline));
+    trampoline->ptr_remain = (uint8_t*)region->free_list_head;
+    region->free_list_head = trampoline;
+}
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 // Transactions
 
@@ -102,3 +112,45 @@ mach_error_t detour_transaction_begin()
 
     return s_pending_error;
 }
+
+mach_error_t detour_transaction_abort()
+{
+    if (s_transaction_thread != mach_thread_self()) {
+        return detour_err_wrong_thread;
+    }
+
+    // Restore all the page permissions.
+    const mach_port_t port = mach_task_self();
+    for (detour_operation* operation = s_pending_operations_head; operation != nullptr;) {
+        DETOUR_CHECK(mach_vm_protect(port, (mach_vm_address_t)operation->target, operation->trampoline->restore_code_size, false, operation->perm));
+
+        if (operation->kind == detour_operation_kind_attach) {
+            if (operation->trampoline) {
+                internal_detour_free_trampoline(operation->trampoline);
+                operation->trampoline = nullptr;
+            }
+        }
+
+        detour_operation* next = operation->next;
+        free(operation);
+        operation = next;
+    }
+    s_pending_operations_head = nullptr;
+
+    // Make sure the trampoline pages are no longer writable.
+    internal_detour_runnable_trampoline_regions();
+
+    // Resume any suspended threads.
+    for (detour_pending_thread* thread = s_pending_threads_head; thread != nullptr;) {
+        // There is nothing we can do if this fails.
+        DETOUR_CHECK(thread_resume(thread->thread));
+
+        detour_pending_thread* next = thread->next;
+        free(thread);
+        thread = next;
+    }
+    s_pending_threads_head = nullptr;
+    s_transaction_thread = THREAD_NULL;
+
+    return err_none;
+}