diff --git a/configure b/configure
index a9293a7..6e2e065 100755
--- a/configure
+++ b/configure
@@ -4128,8 +4128,8 @@ printf "%s\n" "#define HAVE_LIBPNG 1" >>confdefs.h
 
 	CPPFLAGS="$($PKGCONFIG --cflags libpng16) -DHAVE_LIBPNG=1 $CPPFLAGS"
 	LIBS="$($PKGCONFIG --libs libpng16) -lz $LIBS"
-	PKGCONFIG_LIBPNG="libpng >= 1.6,"
 	PKGCONFIG_LIBS_PRIVATE="$($PKGCONFIG --libs libpng16) $PKGCONFIG_LIBS_PRIVATE"
+	PKGCONFIG_REQUIRES="libpng >= 1.6,$PKGCONFIG_REQUIRES"
 
 else $as_nop
 
diff --git a/configure.ac b/configure.ac
index 19caff4..d062b49 100644
--- a/configure.ac
+++ b/configure.ac
@@ -134,8 +134,8 @@ AS_IF([test "x$PKGCONFIG" != x -a x$enable_libpng != xno], [
 	AC_DEFINE([HAVE_LIBPNG], 1, [Have PNG library?])
 	CPPFLAGS="$($PKGCONFIG --cflags libpng16) -DHAVE_LIBPNG=1 $CPPFLAGS"
 	LIBS="$($PKGCONFIG --libs libpng16) -lz $LIBS"
-	PKGCONFIG_LIBPNG="libpng >= 1.6,"
 	PKGCONFIG_LIBS_PRIVATE="$($PKGCONFIG --libs libpng16) $PKGCONFIG_LIBS_PRIVATE"
+	PKGCONFIG_REQUIRES="libpng >= 1.6,$PKGCONFIG_REQUIRES"
     ], [
 	AC_MSG_RESULT([no]);
 	AS_IF([test x$enable_libpng = xyes], [
diff --git a/pdfio.pc.in b/pdfio.pc.in
index b869e79..7196046 100644
--- a/pdfio.pc.in
+++ b/pdfio.pc.in
@@ -7,7 +7,7 @@ Name: pdfio
 Description: PDF read/write library
 Version: @PDFIO_VERSION@
 URL: https://www.msweet.org/pdfio
-Requires: @PKGCONFIG_REQUIRES@
+Cflags: @PKGCONFIG_CFLAGS@
 Libs: @PKGCONFIG_LIBS@
 Libs.private: @PKGCONFIG_LIBS_PRIVATE@
-Cflags: @PKGCONFIG_CFLAGS@
+Requires: @PKGCONFIG_REQUIRES@