diff --git a/backend/CMakeLists.txt b/backend/CMakeLists.txt
index 1b81ad06..3e7ea256 100644
--- a/backend/CMakeLists.txt
+++ b/backend/CMakeLists.txt
@@ -5,7 +5,7 @@ project(zint)
 find_package(PNG)
 find_package(Qr)
 
-set(zint_COMMON_SRCS common.c png.c library.c ps.c large.c reedsol.c)
+set(zint_COMMON_SRCS common.c library.c ps.c large.c reedsol.c)
 set(zint_ONEDIM_SRCS code.c code128.c 2of5.c upcean.c telepen.c medical.c plessey.c rss.c)
 set(zint_POSTAL_SRCS postal.c auspost.c imail.c)
 set(zint_TWODIM_SRCS code16k.c blockf.c dmatrix.c dm200.c pdf417.c qr.c maxicode.c composite.c aztec.c)
@@ -13,6 +13,7 @@ set(zint_SRCS ${zint_COMMON_SRCS} ${zint_ONEDIM_SRCS} ${zint_POSTAL_SRCS} ${zint
 
 if(PNG_FOUND)
     include_directories( ${PNG_INCLUDES} )
+    set(zint_SRCS ${zint_SRCS} png.c)
 else(PNG_FOUND)
     add_definitions (-DNO_PNG)
 endif(PNG_FOUND)
diff --git a/backend/aztec.c b/backend/aztec.c
index 01283f7c..26a8e584 100644
--- a/backend/aztec.c
+++ b/backend/aztec.c
@@ -1016,4 +1016,4 @@ int aztec(struct zint_symbol *symbol, unsigned char source[])
 	}
 	
 	return err_code;
-}
\ No newline at end of file
+}
diff --git a/backend/library.c b/backend/library.c
index 51448f57..e65058dc 100644
--- a/backend/library.c
+++ b/backend/library.c
@@ -109,7 +109,10 @@ extern int codablock(struct zint_symbol *symbol, unsigned char source[]); /* Cod
 extern int daft_code(struct zint_symbol *symbol, unsigned char source[]); /* DAFT Code */
 extern int ean_14(struct zint_symbol *symbol, unsigned char source[]); /* EAN-14 */
 
+#ifndef NO_PNG
 extern int png_plot(struct zint_symbol *symbol);
+#endif
+
 extern int ps_plot(struct zint_symbol *symbol);
 
 int ZBarcode_Encode(struct zint_symbol *symbol, unsigned char *input)
diff --git a/backend/png.c b/backend/png.c
index 771cf6eb..a8e5f049 100644
--- a/backend/png.c
+++ b/backend/png.c
@@ -55,7 +55,6 @@ static void writepng_error_handler(png_structp png_ptr, png_const_charp msg)
 
 int png_to_file(struct zint_symbol *symbol, int image_height, int image_width, char *pixelbuf, int rotate_angle)
 {
-#ifndef NO_PNG
 	struct mainprog_info_type wpng_info;
 	struct mainprog_info_type *graphic;
 	unsigned char outdata[image_width * 3];
@@ -270,7 +269,6 @@ int png_to_file(struct zint_symbol *symbol, int image_height, int image_width, c
 	/* make sure we have disengaged */
 	if (png_ptr && info_ptr) png_destroy_write_struct(&png_ptr, &info_ptr);
 	fclose(wpng_info.outfile);
-#endif
 	return 0;
 }
 
diff --git a/backend_qt4/CMakeLists.txt b/backend_qt4/CMakeLists.txt
index 72844281..4431c27d 100644
--- a/backend_qt4/CMakeLists.txt
+++ b/backend_qt4/CMakeLists.txt
@@ -2,7 +2,7 @@
 
 project(QZint)
 
-include_directories(BEFORE ../backend )
+include_directories(BEFORE "${CMAKE_SOURCE_DIR}/backend" )
 
 set(QZint_SRCS qzint.cpp)
 
@@ -19,7 +19,7 @@ set_target_properties(QZint PROPERTIES	VERSION ${ZINT_VERSION}
 
 add_dependencies(QZint zint)
 
-link_directories( "../backend" )
+link_directories( "${CMAKE_BINARY_DIR}/backend" )
 
 target_link_libraries(QZint zint ${QT_QTGUI_LIBRARY} 
         ${QT_QTCORE_LIBRARY} )