diff --git a/include/log.h b/include/log.h
index a01e41c..df0c7e5 100644
--- a/include/log.h
+++ b/include/log.h
@@ -5,6 +5,12 @@
 
 #define LOG_FILENAME "/tmp/emp.log"
 
+enum log_errcode {
+    OK = 1,
+    ERR_OOM,            // out of memory
+    ERR_OOB,            // out of bounds
+};
+
 extern void log_write(int, const char *, ...);
 extern void log_close();
 extern void log_open(FILE *);
diff --git a/include/vm_segment.h b/include/vm_segment.h
index e813b8c..029759d 100644
--- a/include/vm_segment.h
+++ b/include/vm_segment.h
@@ -2,6 +2,7 @@
 #define _VM_SEGMENT_H_
 
 #include "vm_bits.h"
+#include "log.h"
 
 /*
  * The bounds check is just some inline code to try and cut down on the
@@ -22,10 +23,10 @@ typedef struct {
 	vm_8bit *memory;
 } vm_segment;
 
-extern void vm_segment_copy(vm_segment *, vm_segment *, size_t, size_t, size_t);
+extern int vm_segment_copy(vm_segment *, vm_segment *, size_t, size_t, size_t);
 extern vm_segment *vm_segment_create(size_t);
 extern void vm_segment_free(vm_segment *);
 extern vm_8bit vm_segment_get(vm_segment *, size_t);
-extern void vm_segment_set(vm_segment *, size_t, vm_8bit);
+extern int vm_segment_set(vm_segment *, size_t, vm_8bit);
 
 #endif
diff --git a/src/vm_segment.c b/src/vm_segment.c
index 3977206..da72f3f 100644
--- a/src/vm_segment.c
+++ b/src/vm_segment.c
@@ -58,7 +58,7 @@ vm_segment_free(vm_segment *segment)
  * bounds-checking here will _crash_ the program if we are
  * out-of-bounds.
  */
-void
+int
 vm_segment_set(vm_segment *segment, size_t index, vm_8bit value)
 {
     // Some bounds checking.
@@ -68,13 +68,11 @@ vm_segment_set(vm_segment *segment, size_t index, vm_8bit value)
             index,
             segment->size);
 
-        // We prefer to exit in this scenario, rather than try to
-        // "handle" it with an overflow, because we would rather a crash
-        // over ill-defined behavior.
-        exit(1);
+        return ERR_OOB;
     }
 
     segment->memory[index] = value;
+    return OK;
 }
 
 /*
@@ -102,7 +100,7 @@ vm_segment_get(vm_segment *segment, size_t index)
  * Copy a set of bytes from `src` (at `src_index`) to `dest` (at
  * `dest_index`), such that the range is `length` bytes long.
  */
-void
+int
 vm_segment_copy(vm_segment *dest, 
             vm_segment *src, 
             size_t dest_index, 
@@ -116,7 +114,7 @@ vm_segment_copy(vm_segment *dest,
             length,
             src->size);
 
-        exit(1);
+        return ERR_OOB;
     }
 
     if (dest_index + length >= dest->size) {
@@ -126,10 +124,12 @@ vm_segment_copy(vm_segment *dest,
             length,
             dest->size);
 
-        exit(1);
+        return ERR_OOB;
     }
 
     memcpy(dest->memory + dest_index, 
            src->memory + src_index, 
            length * sizeof(src->memory[src_index]));
+
+    return OK;
 }
diff --git a/tests/vm_segment.c b/tests/vm_segment.c
index 26d8ad4..084277d 100644
--- a/tests/vm_segment.c
+++ b/tests/vm_segment.c
@@ -23,7 +23,7 @@ Test(vm_segment, set) {
     segment = vm_segment_create(length);
     cr_assert_neq(segment, NULL);
 
-    vm_segment_set(segment, index, value);
+    cr_assert_eq(vm_segment_set(segment, index, value), OK);
 
     cr_assert_eq(segment->memory[index], value);
     vm_segment_free(segment);
@@ -56,7 +56,7 @@ Test(vm_segment, copy) {
     vm_segment_set(src, 2, 0xBE);
     vm_segment_set(src, 3, 0xEF);
 
-    vm_segment_copy(dest, src, 8, 0, 4);
+    cr_assert_eq(vm_segment_copy(dest, src, 8, 0, 4), OK);
 
     cr_assert_eq(vm_segment_get(dest, 8), 0xDE);
     cr_assert_eq(vm_segment_get(dest, 9), 0xAD);