diff --git a/libziparchive/zip_archive.cc b/libziparchive/zip_archive.cc
index a64b3b155..efe10966e 100644
--- a/libziparchive/zip_archive.cc
+++ b/libziparchive/zip_archive.cc
@@ -62,68 +62,6 @@ static const bool kCrcChecksEnabled = false;
 // The maximum number of bytes to scan backwards for the EOCD start.
 static const uint32_t kMaxEOCDSearch = kMaxCommentLen + sizeof(EocdRecord);
 
-static const char* kErrorMessages[] = {
-  "Unknown return code.",
-  "Iteration ended",
-  "Zlib error",
-  "Invalid file",
-  "Invalid handle",
-  "Duplicate entries in archive",
-  "Empty archive",
-  "Entry not found",
-  "Invalid offset",
-  "Inconsistent information",
-  "Invalid entry name",
-  "I/O Error",
-  "File mapping failed"
-};
-
-static const int32_t kErrorMessageUpperBound = 0;
-
-static const int32_t kIterationEnd = -1;
-
-// We encountered a Zlib error when inflating a stream from this file.
-// Usually indicates file corruption.
-static const int32_t kZlibError = -2;
-
-// The input file cannot be processed as a zip archive. Usually because
-// it's too small, too large or does not have a valid signature.
-static const int32_t kInvalidFile = -3;
-
-// An invalid iteration / ziparchive handle was passed in as an input
-// argument.
-static const int32_t kInvalidHandle = -4;
-
-// The zip archive contained two (or possibly more) entries with the same
-// name.
-static const int32_t kDuplicateEntry = -5;
-
-// The zip archive contains no entries.
-static const int32_t kEmptyArchive = -6;
-
-// The specified entry was not found in the archive.
-static const int32_t kEntryNotFound = -7;
-
-// The zip archive contained an invalid local file header pointer.
-static const int32_t kInvalidOffset = -8;
-
-// The zip archive contained inconsistent entry information. This could
-// be because the central directory & local file header did not agree, or
-// if the actual uncompressed length or crc32 do not match their declared
-// values.
-static const int32_t kInconsistentInformation = -9;
-
-// An invalid entry name was encountered.
-static const int32_t kInvalidEntryName = -10;
-
-// An I/O related system call (read, lseek, ftruncate, map) failed.
-static const int32_t kIoError = -11;
-
-// We were not able to mmap the central directory or entry contents.
-static const int32_t kMmapFailed = -12;
-
-static const int32_t kErrorMessageLowerBound = -13;
-
 /*
  * A Read-only Zip archive.
  *
@@ -1106,11 +1044,17 @@ int32_t ExtractEntryToFile(ZipArchiveHandle handle,
 }
 
 const char* ErrorCodeString(int32_t error_code) {
-  if (error_code > kErrorMessageLowerBound && error_code < kErrorMessageUpperBound) {
-    return kErrorMessages[error_code * -1];
+  // Make sure that the number of entries in kErrorMessages and ErrorCodes
+  // match.
+  static_assert((-kLastErrorCode + 1) == arraysize(kErrorMessages),
+                "(-kLastErrorCode + 1) != arraysize(kErrorMessages)");
+
+  const uint32_t idx = -error_code;
+  if (idx < arraysize(kErrorMessages)) {
+    return kErrorMessages[idx];
   }
 
-  return kErrorMessages[0];
+  return "Unknown return code";
 }
 
 int GetFileDescriptor(const ZipArchiveHandle handle) {
diff --git a/libziparchive/zip_archive_private.h b/libziparchive/zip_archive_private.h
index 971db4f12..de93ecdd1 100644
--- a/libziparchive/zip_archive_private.h
+++ b/libziparchive/zip_archive_private.h
@@ -26,6 +26,69 @@
 
 #include <utils/FileMap.h>
 #include <ziparchive/zip_archive.h>
+#include "android-base/macros.h"
+
+static const char* kErrorMessages[] = {
+    "Success",
+    "Iteration ended",
+    "Zlib error",
+    "Invalid file",
+    "Invalid handle",
+    "Duplicate entries in archive",
+    "Empty archive",
+    "Entry not found",
+    "Invalid offset",
+    "Inconsistent information",
+    "Invalid entry name",
+    "I/O error",
+    "File mapping failed",
+};
+
+enum ErrorCodes : int32_t {
+  kIterationEnd = -1,
+
+  // We encountered a Zlib error when inflating a stream from this file.
+  // Usually indicates file corruption.
+  kZlibError = -2,
+
+  // The input file cannot be processed as a zip archive. Usually because
+  // it's too small, too large or does not have a valid signature.
+  kInvalidFile = -3,
+
+  // An invalid iteration / ziparchive handle was passed in as an input
+  // argument.
+  kInvalidHandle = -4,
+
+  // The zip archive contained two (or possibly more) entries with the same
+  // name.
+  kDuplicateEntry = -5,
+
+  // The zip archive contains no entries.
+  kEmptyArchive = -6,
+
+  // The specified entry was not found in the archive.
+  kEntryNotFound = -7,
+
+  // The zip archive contained an invalid local file header pointer.
+  kInvalidOffset = -8,
+
+  // The zip archive contained inconsistent entry information. This could
+  // be because the central directory & local file header did not agree, or
+  // if the actual uncompressed length or crc32 do not match their declared
+  // values.
+  kInconsistentInformation = -9,
+
+  // An invalid entry name was encountered.
+  kInvalidEntryName = -10,
+
+  // An I/O related system call (read, lseek, ftruncate, map) failed.
+  kIoError = -11,
+
+  // We were not able to mmap the central directory or entry contents.
+  kMmapFailed = -12,
+
+  kLastErrorCode = kMmapFailed,
+};
 
 class MappedZipFile {
  public:
diff --git a/libziparchive/zip_archive_test.cc b/libziparchive/zip_archive_test.cc
index 42167ddec..52099c3b5 100644
--- a/libziparchive/zip_archive_test.cc
+++ b/libziparchive/zip_archive_test.cc
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#include "zip_archive_private.h"
+
 #include <errno.h>
 #include <fcntl.h>
 #include <getopt.h>
@@ -708,8 +710,7 @@ TEST(ziparchive, InvalidDataDescriptors) {
   int32_t error_code = 0;
   ExtractEntryToMemory(invalid_csize, &entry, &error_code);
 
-  ASSERT_GT(0, error_code);
-  ASSERT_STREQ("Inconsistent information", ErrorCodeString(error_code));
+  ASSERT_EQ(kInconsistentInformation, error_code);
 
   std::vector<uint8_t> invalid_size = kDataDescriptorZipFile;
   invalid_csize[kSizeOffset] = 0xfe;
@@ -718,8 +719,17 @@ TEST(ziparchive, InvalidDataDescriptors) {
   entry.clear();
   ExtractEntryToMemory(invalid_csize, &entry, &error_code);
 
-  ASSERT_GT(0, error_code);
-  ASSERT_STREQ("Inconsistent information", ErrorCodeString(error_code));
+  ASSERT_EQ(kInconsistentInformation, error_code);
+}
+
+TEST(ziparchive, ErrorCodeString) {
+  ASSERT_STREQ("Success", ErrorCodeString(0));
+
+  // Out of bounds.
+  ASSERT_STREQ("Unknown return code", ErrorCodeString(1));
+  ASSERT_STREQ("Unknown return code", ErrorCodeString(-13));
+
+  ASSERT_STREQ("I/O error", ErrorCodeString(kIoError));
 }
 
 int main(int argc, char** argv) {