diff --git a/include/vm_segment.h b/include/vm_segment.h
index 8a3b0db..deb00bb 100644
--- a/include/vm_segment.h
+++ b/include/vm_segment.h
@@ -55,11 +55,12 @@ struct vm_segment {
 
 extern int vm_segment_copy(vm_segment *, vm_segment *, size_t, size_t, size_t);
 extern int vm_segment_fread(vm_segment *, FILE *, size_t);
-extern int vm_segment_read_map(vm_segment *, size_t, void *, vm_segment_read_fn);
+extern int vm_segment_read_map(vm_segment *, size_t, vm_segment_read_fn);
 extern int vm_segment_set(vm_segment *, size_t, vm_8bit);
-extern int vm_segment_write_map(vm_segment *, size_t, void *, vm_segment_write_fn);
+extern int vm_segment_write_map(vm_segment *, size_t, vm_segment_write_fn);
 extern vm_8bit vm_segment_get(vm_segment *, size_t);
 extern vm_segment *vm_segment_create(size_t);
 extern void vm_segment_free(vm_segment *);
+extern void vm_segment_set_map_machine(void *);
 
 #endif
diff --git a/src/vm_segment.c b/src/vm_segment.c
index d895237..2c5c7f9 100644
--- a/src/vm_segment.c
+++ b/src/vm_segment.c
@@ -14,6 +14,18 @@
 #include "log.h"
 #include "vm_segment.h"
 
+/*
+ * This is sort of regrettable, but we need a machine pointer that we
+ * can pass into the read/write map functions (which will assume to have
+ * access to the machine architecture). The alternative is an update to
+ * a lot more of the codebase to add machine pointers -- void pointers
+ * at that -- which is even uglier.
+ *
+ * FIXME: we might consider a dependency injection container at some
+ * point.
+ */
+static void *map_mach = NULL;
+
 /*
  * Create a new segment, such that it contains a number of bytes indicated
  * by `size`. 
@@ -100,7 +112,7 @@ vm_segment_set(vm_segment *segment, size_t index, vm_8bit value)
 
     // Check if we have a write mapper
     if (segment->write_table[index]) {
-        segment->write_table[index](segment, index, value);
+        segment->write_table[index](segment, index, value, map_mach);
         return OK;
     }
 
@@ -128,7 +140,7 @@ vm_segment_get(vm_segment *segment, size_t index)
 
     // We may have a read mapper for this address
     if (segment->read_table[index]) {
-        return segment->read_table[index](segment, index);
+        return segment->read_table[index](segment, index, map_mach);
     }
 
     return segment->memory[index];
@@ -229,3 +241,12 @@ vm_segment_fread(vm_segment *segment, FILE *stream, size_t len)
 
     return OK;
 }
+
+/*
+ * Change the internal notion of the machine used by map functions
+ */
+void
+vm_segment_set_map_machine(void *mach)
+{
+    map_mach = mach;
+}