diff --git a/convert/convert.h b/convert/convert.h
index b6f6d8a..3f23f9e 100644
--- a/convert/convert.h
+++ b/convert/convert.h
@@ -6,6 +6,7 @@
 /* convert.h - character set conversion routines. */
 
 #include "lib/defs.h"
+#include "lib/error.h"
 
 enum {
 	/* Constants for CR and LF. Note that we should not use '\n' or '\r'
diff --git a/lib/BUILD.bazel b/lib/BUILD.bazel
index 4c48ef4..5d0502f 100644
--- a/lib/BUILD.bazel
+++ b/lib/BUILD.bazel
@@ -12,6 +12,7 @@ cc_library(
         "crc32.h",
         "defs.h",
         "endian.h",
+        "error.h",
         "util.h",
     ],
     copts = COPTS,
diff --git a/lib/defs.h b/lib/defs.h
index 589ae8f..ae29254 100644
--- a/lib/defs.h
+++ b/lib/defs.h
@@ -90,25 +90,6 @@ typedef long Size;
 
 #endif
 
-// =============================================================================
-// Error codes and error reporting
-// =============================================================================
-
-// Error codes.
-typedef enum {
-	// No error (success). Equal to 0.
-	kErrorOK,
-
-	// Memory allocation failed.
-	kErrorNoMemory,
-
-	// Invaild table data.
-	kErrorBadData,
-
-	// Too many files in one directory.
-	kErrorDirectoryTooLarge
-} ErrorCode;
-
 // =============================================================================
 // Memory allocation
 // =============================================================================
diff --git a/lib/error.h b/lib/error.h
new file mode 100644
index 0000000..7da7664
--- /dev/null
+++ b/lib/error.h
@@ -0,0 +1,22 @@
+// Copyright 2022 Dietrich Epp.
+// This file is part of SyncFiles. SyncFiles is licensed under the terms of the
+// Mozilla Public License, version 2.0. See LICENSE.txt for details.
+#ifndef LIB_ERROR_H
+#define LIB_ERROR_H
+
+// Error codes.
+typedef enum {
+	// No error (success). Equal to 0.
+	kErrorOK,
+
+	// Memory allocation failed.
+	kErrorNoMemory,
+
+	// Invaild table data.
+	kErrorBadData,
+
+	// Too many files in one directory.
+	kErrorDirectoryTooLarge,
+} ErrorCode;
+
+#endif
diff --git a/lib/test.h b/lib/test.h
index e56028d..4739251 100644
--- a/lib/test.h
+++ b/lib/test.h
@@ -6,6 +6,7 @@
 // test.h - unit testing definitions.
 
 #include "lib/defs.h"
+#include "lib/error.h"
 
 // The number of test failures.
 extern int gFailCount;
diff --git a/lib/util.h b/lib/util.h
index 6ba0a1a..424154d 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -3,7 +3,7 @@
 // Mozilla Public License, version 2.0. See LICENSE.txt for details.
 #ifndef LIB_UTIL_H
 #define LIB_UTIL_H
-#include "lib/defs.h"
+#include "lib/error.h"
 
 // Print an error message and exit.
 void Fatalf(const char *msg, ...)
diff --git a/sync/tree.c b/sync/tree.c
index a697c50..0289e6d 100644
--- a/sync/tree.c
+++ b/sync/tree.c
@@ -3,6 +3,8 @@
 // Mozilla Public License, version 2.0. See LICENSE.txt for details.
 #include "sync/tree.h"
 
+#include "lib/error.h"
+
 #include <stdio.h>
 
 #define GetNode(nodes, ref) ((nodes) + (ref)-1)