diff --git a/convert/BUILD.bazel b/convert/BUILD.bazel
index ee554f1..bd2a938 100644
--- a/convert/BUILD.bazel
+++ b/convert/BUILD.bazel
@@ -28,15 +28,15 @@ cc_library(
         "convert.c",
         "convert_1f.c",
         "convert_1r.c",
-        "toolbox.c",
     ],
     hdrs = [
         "convert.h",
         "data.h",
-        "defs.h",
-        "test.h",
     ],
     copts = COPTS,
+    deps = [
+        "//lib",
+    ],
 )
 
 cc_test(
@@ -47,5 +47,6 @@ cc_test(
     copts = COPTS,
     deps = [
         ":convert",
+        "//lib",
     ],
 )
diff --git a/convert/convert.h b/convert/convert.h
index 678ad42..a132958 100644
--- a/convert/convert.h
+++ b/convert/convert.h
@@ -2,7 +2,7 @@
 #define convert_h
 /* convert.h - character set conversion routines. */
 
-#include "convert/defs.h"
+#include "lib/defs.h"
 
 /* Error codes. */
 enum
diff --git a/convert/convert_1f.c b/convert/convert_1f.c
index 474fcef..2408151 100644
--- a/convert/convert_1f.c
+++ b/convert/convert_1f.c
@@ -1,6 +1,6 @@
 /* convert_1f.c - Forward conversion from extended ASCII to UTF-8. */
 #include "convert/convert.h"
-#include "convert/defs.h"
+#include "lib/defs.h"
 
 struct Convert1fData {
 	/* Unicode characters, encoded in UTF-8, and packed MSB first. Always either
diff --git a/convert/convert_1r.c b/convert/convert_1r.c
index cfbab46..68f272b 100644
--- a/convert/convert_1r.c
+++ b/convert/convert_1r.c
@@ -1,6 +1,6 @@
 /* convert_1r.c - Reverse conversion from UTF-8 to extended ASCII. */
 #include "convert/convert.h"
-#include "convert/defs.h"
+#include "lib/defs.h"
 
 enum
 {
diff --git a/convert/convert_test.c b/convert/convert_test.c
index 4e6fa4d..4382618 100644
--- a/convert/convert_test.c
+++ b/convert/convert_test.c
@@ -3,7 +3,7 @@
 
 #include "convert/convert.h"
 #include "convert/data.h"
-#include "convert/test.h"
+#include "lib/test.h"
 
 #include <errno.h>
 #include <stdarg.h>
diff --git a/convert/data.h b/convert/data.h
index 5dd2320..04725d0 100644
--- a/convert/data.h
+++ b/convert/data.h
@@ -1,7 +1,7 @@
 #ifndef data_h
 #define data_h
 /* data.h - charmap data, not used for classic Mac OS builds */
-#include "convert/defs.h"
+#include "lib/defs.h"
 
 /* Get the ID of the given character map. Return NULL if no such character map
    exists. */
diff --git a/lib/BUILD.bazel b/lib/BUILD.bazel
new file mode 100644
index 0000000..163584d
--- /dev/null
+++ b/lib/BUILD.bazel
@@ -0,0 +1,15 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+load("//bazel:copts.bzl", "COPTS")
+
+cc_library(
+    name = "lib",
+    srcs = [
+        "toolbox.c",
+    ],
+    hdrs = [
+        "defs.h",
+        "test.h",
+    ],
+    copts = COPTS,
+    visibility = ["//visibility:public"],
+)
diff --git a/convert/defs.h b/lib/defs.h
similarity index 100%
rename from convert/defs.h
rename to lib/defs.h
diff --git a/convert/test.h b/lib/test.h
similarity index 93%
rename from convert/test.h
rename to lib/test.h
index 1c8d4cc..a803a16 100644
--- a/convert/test.h
+++ b/lib/test.h
@@ -2,7 +2,7 @@
 #define test_h
 /* test.h - unit testing definitions. */
 
-#include "convert/defs.h"
+#include "lib/defs.h"
 
 /* Print an error message and exit. */
 void Dief(const char *msg, ...) __attribute__((noreturn, format(printf, 1, 2)));
diff --git a/convert/toolbox.c b/lib/toolbox.c
similarity index 96%
rename from convert/toolbox.c
rename to lib/toolbox.c
index b2b643d..184d9a5 100644
--- a/convert/toolbox.c
+++ b/lib/toolbox.c
@@ -3,8 +3,8 @@
    This is used to run conversion tests on non-Mac OS systems to make
    development easier. These are not intended to make it possible to port the
    converter to non-Mac OS systems. */
-#include "convert/defs.h"
-#include "convert/test.h"
+#include "lib/defs.h"
+#include "lib/test.h"
 
 #include <stdarg.h>
 #include <stdio.h>