diff --git a/configure.ac b/configure.ac
index dda267bd..9843224d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1188,7 +1188,6 @@ if test x"$with_libspng" != x"no"; then
     [AC_DEFINE(HAVE_SPNG,1,[define if you have libspng installed.])
      with_libspng=yes
      PACKAGES_USED="$PACKAGES_USED spng"
-     with_png=no
     ],
     [
     ]
diff --git a/libvips/foreign/pngload.c b/libvips/foreign/pngload.c
index 1c4d34b0..8092078e 100644
--- a/libvips/foreign/pngload.c
+++ b/libvips/foreign/pngload.c
@@ -50,7 +50,7 @@
 
 #include "pforeign.h"
 
-#ifdef HAVE_PNG
+#if defined(HAVE_PNG) && !defined(HAVE_SPNG)
 
 typedef struct _VipsForeignLoadPng {
 	VipsForeignLoad parent_object;
@@ -387,7 +387,7 @@ vips_foreign_load_png_buffer_init( VipsForeignLoadPngBuffer *buffer )
 {
 }
 
-#endif /*HAVE_PNG*/
+#endif /*defined(HAVE_PNG) && !defined(HAVE_SPNG)*/
 
 /**
  * vips_pngload: