diff --git a/configure.ac b/configure.ac
index 937b2bf..26f17fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -123,7 +123,7 @@ dnl $2 - GD feature name to track
 dnl $3 - lower case name for user
 dnl $4 - test for the feature
 dnl The test code should set gd_found_lib=yes to indicate success.
-m4_define([GD_LIB_CHECK], [dnl
+m4_define([_GD_LIB_CHECK], [dnl
   dnl Export the flag for the user to leverage.  No other logic here.
   AC_MSG_CHECKING([whether to support $3])
   AC_ARG_WITH([$3],
@@ -179,22 +179,23 @@ m4_define([GD_LIB_CHECK], [dnl
   AM_CONDITIONAL([HAVE_$1], test "$gd_found_lib" = yes)
   gd_with_$1=$gd_found_lib
 ])
+dnl Helper to avoid repeating m4_tolower() a lot.
+m4_define([GD_LIB_CHECK], [_GD_LIB_CHECK([$1], [$2], m4_tolower([$2]), [$3])])dnl
 
 dnl Helper macro for working with external libraries with pkg-config support.
-dnl GD_LIB_PKG_CHECK([SYM], [FEATURE], [name], [pkg-config module], [...fallback test...])
+dnl GD_LIB_PKG_CHECK([SYM], [FEATURE], [pkg-config module], [...fallback test...])
 dnl $1 - upper case symbol
 dnl $2 - GD feature name to track
-dnl $3 - lower case name for user
-dnl $4 - pkg-config module to look for
-dnl $5 - fallback test for the feature
+dnl $3 - pkg-config module to look for
+dnl $4 - fallback test for the feature
 m4_define([GD_LIB_PKG_CHECK], [dnl
-  GD_LIB_CHECK([$1], [$2], [$3], [dnl
-    PKG_CHECK_MODULES([$1], [$4], [gd_found_lib=yes gd_require_pkg_name="$4"], [$5])
+  GD_LIB_CHECK([$1], [$2], [dnl
+    PKG_CHECK_MODULES([$1], [$3], [gd_found_lib=yes gd_require_pkg_name="$3"], [$4])
   ])
 ])
 
 dnl Check for zlib support.
-GD_LIB_PKG_CHECK([LIBZ], [ZLIB], [zlib], [zlib], [dnl
+GD_LIB_PKG_CHECK([LIBZ], [ZLIB], [zlib], [dnl
   AC_CHECK_LIB([z], [deflate], [dnl
     AS_VAR_APPEND([LIBZ_LIBS], [" -lz"])
     gd_found_lib=yes
@@ -202,7 +203,7 @@ GD_LIB_PKG_CHECK([LIBZ], [ZLIB], [zlib], [zlib], [dnl
 ])
 
 dnl Check for libpng support.
-GD_LIB_PKG_CHECK([LIBPNG], [PNG], [png], [libpng], [
+GD_LIB_PKG_CHECK([LIBPNG], [PNG], [libpng], [
   LIBPNG_CONFIG=$gd_with_lib/bin/libpng-config
   AC_MSG_CHECKING([for $LIBPNG_CONFIG script])
   if test -e "$LIBPNG_CONFIG"; then
@@ -217,7 +218,7 @@ GD_LIB_PKG_CHECK([LIBPNG], [PNG], [png], [libpng], [
 
 dnl Check for FreeType support.
 dnl NB: "9.8.3" corresponds to freetype-2.1.10.
-GD_LIB_PKG_CHECK([LIBFREETYPE], [FREETYPE], [freetype], [freetype2 >= 9.8.3], [
+GD_LIB_PKG_CHECK([LIBFREETYPE], [FREETYPE], [freetype2 >= 9.8.3], [
   FREETYPE_CONFIG=$gd_with_lib/bin/freetype-config
   AC_MSG_CHECKING([for $FREETYPE_CONFIG script])
   if test -e "$FREETYPE_CONFIG"; then
@@ -234,7 +235,7 @@ if test "$gd_with_LIBFREETYPE" = "yes"; then
 fi
 
 dnl Check for Raqm support.
-GD_LIB_PKG_CHECK([LIBRAQM], [RAQM], [raqm], [raqm], [
+GD_LIB_PKG_CHECK([LIBRAQM], [RAQM], [raqm], [
   AC_CHECK_LIB([raqm], [raqm_create], [dnl
     AS_VAR_APPEND([LIBRAQM_LIBS], [" -lraqm -lfreetype"])
     gd_found_lib=yes
@@ -242,7 +243,7 @@ GD_LIB_PKG_CHECK([LIBRAQM], [RAQM], [raqm], [raqm], [
 ])
 
 dnl Check for fontconfig support.
-GD_LIB_PKG_CHECK([LIBFONTCONFIG], [FONTCONFIG], [fontconfig], [fontconfig], [
+GD_LIB_PKG_CHECK([LIBFONTCONFIG], [FONTCONFIG], [fontconfig], [
   AC_CHECK_LIB([fontconfig], [FcInit], [dnl
     AS_VAR_APPEND([LIBFONTCONFIG_LIBS], [" -lfontconfig"])
     gd_found_lib=yes
@@ -250,7 +251,7 @@ GD_LIB_PKG_CHECK([LIBFONTCONFIG], [FONTCONFIG], [fontconfig], [fontconfig], [
 ])
 
 dnl Check for jpeg support.
-GD_LIB_PKG_CHECK([LIBJPEG], [JPEG], [jpeg], [libjpeg], [
+GD_LIB_PKG_CHECK([LIBJPEG], [JPEG], [libjpeg], [
   AC_CHECK_LIB([jpeg], [jpeg_set_defaults], [dnl
     AS_VAR_APPEND([LIBJPEG_LIBS], [" -ljpeg"])
     gd_found_lib=yes
@@ -258,7 +259,7 @@ GD_LIB_PKG_CHECK([LIBJPEG], [JPEG], [jpeg], [libjpeg], [
 ])
 
 dnl Check for libimagequant support.
-GD_LIB_CHECK([LIBIMAGEQUANT], [LIQ], [liq], [
+GD_LIB_CHECK([LIBIMAGEQUANT], [LIQ], [
   AC_CHECK_HEADER([libimagequant.h], [
     save_CFLAGS=$CFLAGS
     CFLAGS="$CFLAGS $OPENMP_CFLAGS"
@@ -271,7 +272,7 @@ GD_LIB_CHECK([LIBIMAGEQUANT], [LIQ], [liq], [
 ])
 
 dnl Check for xpm support.
-GD_LIB_PKG_CHECK([LIBXPM], [XPM], [xpm], [xpm], [
+GD_LIB_PKG_CHECK([LIBXPM], [XPM], [xpm], [
   AC_CHECK_LIB([Xpm], [XpmReadFileToXpmImage], [dnl
     AS_VAR_APPEND([LIBXPM_LIBS], [" -lXpm"])
     gd_found_lib=yes
@@ -279,7 +280,7 @@ GD_LIB_PKG_CHECK([LIBXPM], [XPM], [xpm], [xpm], [
 ])
 
 dnl Check for tiff support.
-GD_LIB_PKG_CHECK([LIBTIFF], [TIFF], [tiff], [libtiff-4], [
+GD_LIB_PKG_CHECK([LIBTIFF], [TIFF], [libtiff-4], [
   AC_CHECK_LIB([tiff], [TIFFClientOpen], [dnl
     AS_VAR_APPEND([LIBTIFF_LIBS], [" -ltiff"])
     gd_found_lib=yes
@@ -287,7 +288,7 @@ GD_LIB_PKG_CHECK([LIBTIFF], [TIFF], [tiff], [libtiff-4], [
 ])
 
 dnl Check for webp support.
-GD_LIB_PKG_CHECK([LIBWEBP], [WEBP], [webp], [libwebp >= 0.2.0], [
+GD_LIB_PKG_CHECK([LIBWEBP], [WEBP], [libwebp >= 0.2.0], [
   AC_CHECK_LIB([webp], [WebPGetInfo], [dnl
     AS_VAR_APPEND([LIBWEBP_LIBS], [" -lwebp"])
     gd_found_lib=yes
@@ -295,14 +296,14 @@ GD_LIB_PKG_CHECK([LIBWEBP], [WEBP], [webp], [libwebp >= 0.2.0], [
 ])
 
 dnl Check for heif support.
-GD_LIB_PKG_CHECK([LIBHEIF], [HEIF], [heif], [libheif >= 1.7.0], [
+GD_LIB_PKG_CHECK([LIBHEIF], [HEIF], [libheif >= 1.7.0], [
   AC_CHECK_LIB([heif], [heif_get_version], [dnl
     AS_VAR_APPEND([LIBHEIF_LIBS], [" -lheif"])
   ])
 ])
 
 dnl Check for avif support.
-GD_LIB_PKG_CHECK([LIBAVIF], [AVIF], [avif], [libavif >= 0.8.2], [
+GD_LIB_PKG_CHECK([LIBAVIF], [AVIF], [libavif >= 0.8.2], [
   AC_CHECK_LIB([avif], [avifVersion], [dnl
     AS_VAR_APPEND([LIBAVIF_LIBS], [" -lavif"])
     gd_found_lib=yes