diff --git a/backend/common.h b/backend/common.h
index a1c44fb6..3b7c7423 100644
--- a/backend/common.h
+++ b/backend/common.h
@@ -41,11 +41,16 @@ extern "C" {
 #define ARRAY_SIZE(x) ((int) (sizeof(x) / sizeof((x)[0])))
 #endif
 
+/* Determine if C89 (excluding MSVC, which doesn't define __STDC_VERSION__) */
+#if !defined(_MSC_VER) && (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199000L)
+#define ZINT_IS_C89
+#endif
+
 #ifdef _MSC_VER
 #  include <malloc.h>
 #  define z_alloca(nmemb) _alloca(nmemb)
 #else
-#  if (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199000L) || defined(__NuttX__) /* C89 or NuttX RTOS */
+#  if defined(ZINT_IS_C89) || defined(__NuttX__) /* C89 or NuttX RTOS */
 #    include <alloca.h>
 #  endif
 #  define z_alloca(nmemb) alloca(nmemb)
@@ -101,14 +106,13 @@ typedef unsigned __int64 uint64_t;
 #define ustrcat(target, source) strcat((char *) (target), (const char *) (source))
 #define ustrncat(target, source, count) strncat((char *) (target), (const char *) (source), (count))
 
-/* VC6 or C89 */
-#if (defined(_MSC_VER) && _MSC_VER == 1200) || (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199000L)
+#if (defined(_MSC_VER) && _MSC_VER == 1200) || defined(ZINT_IS_C89) /* VC6 or C89 */
 #  define ceilf (float) ceil
 #  define floorf (float) floor
 #  define fmodf (float) fmod
 #endif
 /* `round()` (C99) not before MSVC 2013 (C++ 12.0) */
-#if (defined(_MSC_VER) && _MSC_VER < 1800) || (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199000L)
+#if (defined(_MSC_VER) && _MSC_VER < 1800) || defined(ZINT_IS_C89)
 #  define round(arg) floor((arg) + 0.5)
 #  define roundf(arg) floorf((arg) + 0.5f)
 #endif
diff --git a/backend/tests/testcommon.c b/backend/tests/testcommon.c
index 2cc44dc5..77a2a16b 100644
--- a/backend/tests/testcommon.c
+++ b/backend/tests/testcommon.c
@@ -34,24 +34,22 @@
 /* Due to above: */
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
-#include "testcommon.h"
-
 #ifdef _WIN32
 #include <windows.h>
 #include <direct.h>
 #endif
-
-#include "../eci.h"
 #ifndef NO_PNG
 #include <png.h>
 #include <zlib.h>
 #include <setjmp.h>
 #endif
 #include <assert.h>
-#include <errno.h>
 #include <limits.h>
 #include <sys/stat.h>
 
+#include "testcommon.h"
+#include "../eci.h"
+
 static int tests = 0;
 static int failed = 0;
 static int skipped = 0;
@@ -63,7 +61,7 @@ static const char *testFunc = NULL;
 
 /* Visual C++ 6 doesn't support variadic args to macros, so make do with functions, which have inferior behaviour,
    e.g. don't exit on failure, `assert_equal()` type-specific */
-#if (defined(_MSC_VER) && _MSC_VER == 1200) || (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199000L) /* VC6 or C89 */
+#if (defined(_MSC_VER) && _MSC_VER == 1200) || defined(ZINT_IS_C89) /* VC6 or C89 */
 #include <stdarg.h>
 void assert_zero(int exp, const char *fmt, ...) {
     assertionNum++;
diff --git a/backend/tests/testcommon.h b/backend/tests/testcommon.h
index 507c86c5..3c4ae3c6 100644
--- a/backend/tests/testcommon.h
+++ b/backend/tests/testcommon.h
@@ -57,7 +57,7 @@ extern "C" {
 #define testutil_pclose(stream) _pclose(stream)
 #else
 #include <unistd.h>
-#  if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 199000L /* C89 */
+#  if defined(ZINT_IS_C89)
     extern FILE *popen(const char *command, const char *type);
     extern int pclose(FILE *stream);
 #  endif
@@ -101,7 +101,7 @@ typedef struct s_testFunction {
 void testRun(int argc, char *argv[], testFunction funcs[], int funcs_size);
 int testContinue(const testCtx *const p_ctx, const int i);
 
-#if (defined(_MSC_VER) &&_MSC_VER == 1200) || (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199000L) /* VC6 or C89 */
+#if (defined(_MSC_VER) &&_MSC_VER == 1200) || defined(ZINT_IS_C89) /* VC6 or C89 */
 void assert_zero(int exp, const char *fmt, ...);
 void assert_nonzero(int exp, const char *fmt, ...);
 void assert_null(const void *exp, const char *fmt, ...);
diff --git a/backend/zintconfig.h b/backend/zintconfig.h
index dbeebfe3..493fcf49 100644
--- a/backend/zintconfig.h
+++ b/backend/zintconfig.h
@@ -1,4 +1,4 @@
-/*  zintconfig.h - the configured options and settings for libzint */
+/*  zintconfig.h - the configured options and settings for libzint, generated from "zintconfig.h.in" by CMake */
 /*
     libzint - the open source barcode library
     Copyright (C) 2021-2022 Robin Stuart <rstuart114@gmail.com>
diff --git a/backend/zintconfig.h.in b/backend/zintconfig.h.in
index 7f07fa75..3fd78c32 100644
--- a/backend/zintconfig.h.in
+++ b/backend/zintconfig.h.in
@@ -1,7 +1,7 @@
-/*  zintconfig.h - the configured options and settings for libzint
-
+/*  zintconfig.h - the configured options and settings for libzint, generated from "zintconfig.h.in" by CMake */
+/*
     libzint - the open source barcode library
-    Copyright (C) 2021 Robin Stuart <rstuart114@gmail.com>
+    Copyright (C) 2021-2022 Robin Stuart <rstuart114@gmail.com>
 
     Redistribution and use in source and binary forms, with or without
     modification, are permitted provided that the following conditions
@@ -28,7 +28,7 @@
     OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     SUCH DAMAGE.
  */
-/* vim: set ts=4 sw=4 et : */
+/* SPDX-License-Identifier: BSD-3-Clause */
 
 #ifndef ZINTCONFIG_H
 #define ZINTCONFIG_H
@@ -38,4 +38,5 @@
 #define ZINT_VERSION_RELEASE    @ZINT_VERSION_RELEASE@
 #define ZINT_VERSION_BUILD      @ZINT_VERSION_BUILD@
 
+/* vim: set ts=4 sw=4 et : */
 #endif /* ZINTCONFIG_H */