diff --git a/CHANGES.md b/CHANGES.md
index 855cb89..a3303e9 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -6,6 +6,9 @@ v1.6.1 - YYYY-MM-DD
 -------------------
 
 - Added missing input checking to `pdfioFileCreateFontObjFromBase` function.
+- Updated Xcode project to use installed PNG library.
+- Fixed some clang warnings.
+
 
 
 v1.6.0 - 2025-10-06
diff --git a/pdfio-content.c b/pdfio-content.c
index 45cf293..f71277d 100644
--- a/pdfio-content.c
+++ b/pdfio-content.c
@@ -2702,7 +2702,8 @@ copy_png(pdfio_dict_t *dict,		// I - Dictionary
   png_infop	info = NULL;		// PNG info pointers
   png_bytep	*rows = NULL;		// PNG row pointers
   unsigned char	*pixels = NULL;		// PNG image data
-  unsigned	i,			// Looping var
+  int		i;			// Looping var
+  unsigned	y,			// Row
 		color_type,		// PNG color mode
 		width,			// Width in columns
 		height,			// Height in lines
@@ -2800,8 +2801,8 @@ copy_png(pdfio_dict_t *dict,		// I - Dictionary
     goto finish_png;
   }
 
-  for (i = 0; i < height; i ++)
-    rows[i] = pixels + i * linesize;
+  for (y = 0; y < height; y ++)
+    rows[y] = pixels + y * linesize;
 
   // Read the image...
   for (i = png_set_interlace_handling(pp); i > 0; i --)
@@ -2815,7 +2816,7 @@ copy_png(pdfio_dict_t *dict,		// I - Dictionary
   // Grab any color space/palette information...
   if (png_get_PLTE(pp, info, &palette, &num_palette))
   {
-    pdfioDictSetArray(dict, "ColorSpace", pdfioArrayCreateColorFromPalette(dict->pdf, num_palette, (unsigned char *)palette));
+    pdfioDictSetArray(dict, "ColorSpace", pdfioArrayCreateColorFromPalette(dict->pdf, (size_t)num_palette, (unsigned char *)palette));
   }
   else if (png_get_iCCP(pp, info, &icc_name, /*compression_type*/NULL, &icc_data, &icc_datalen))
   {
@@ -3845,14 +3846,12 @@ png_read_func(png_structp pp,		// I - PNG pointer
               png_bytep   data,		// I - Read buffer
               size_t      length)	// I - Number of bytes to read
 {
-  int		*fd = (int *)png_get_io_ptr(pp);
-					// Pointer to file descriptor
-  ssize_t	bytes;			// Bytes read
+  int	*fd = (int *)png_get_io_ptr(pp);// Pointer to file descriptor
 
 
   PDFIO_DEBUG("png_read_func(pp=%p, data=%p, length=%lu)\n", (void *)pp, (void *)data, (unsigned long)length);
 
-  if ((bytes = read(*fd, data, length)) < (ssize_t)length)
+  if (read(*fd, data, length) < (ssize_t)length)
     png_error(pp, "Unable to read from PNG file.");
 }
 #endif // HAVE_LIBPNG
diff --git a/pdfio.xcodeproj/project.pbxproj b/pdfio.xcodeproj/project.pbxproj
index 52bef57..b3fe035 100644
--- a/pdfio.xcodeproj/project.pbxproj
+++ b/pdfio.xcodeproj/project.pbxproj
@@ -379,7 +379,7 @@
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				CODE_SIGN_IDENTITY = "Apple Development";
 				COPY_PHASE_STRIP = NO;
-				CURRENT_PROJECT_VERSION = 1.1.2;
+				CURRENT_PROJECT_VERSION = 1.6.1;
 				DEAD_CODE_STRIPPING = YES;
 				DEBUG_INFORMATION_FORMAT = dwarf;
 				ENABLE_STRICT_OBJC_MSGSEND = YES;
@@ -390,6 +390,9 @@
 				GCC_PREPROCESSOR_DEFINITIONS = (
 					"$(inherited)",
 					"DEBUG=1",
+					"HAVE_LIBPNG=1",
+					"HAVE_TM_GMTOFF=1",
+					"HAVE_TIMEGM=1",
 				);
 				GCC_TREAT_IMPLICIT_FUNCTION_DECLARATIONS_AS_ERRORS = YES;
 				GCC_TREAT_INCOMPATIBLE_POINTER_TYPE_WARNINGS_AS_ERRORS = YES;
@@ -409,10 +412,21 @@
 				GCC_WARN_UNUSED_LABEL = YES;
 				GCC_WARN_UNUSED_PARAMETER = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
+				HEADER_SEARCH_PATHS = (
+					/usr/local/include,
+					/opt/local/include,
+					/opt/homebrew/include,
+				);
 				MACOSX_DEPLOYMENT_TARGET = 11.0;
 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
 				MTL_FAST_MATH = YES;
 				ONLY_ACTIVE_ARCH = YES;
+				OTHER_LDFLAGS = (
+					"-L/usr/local/lib",
+					"-L/opt/local/lib",
+					"-L/opt/homebrew/lib",
+					"-lpng16",
+				);
 				RUN_CLANG_STATIC_ANALYZER = YES;
 				SDKROOT = macosx;
 				STRING_CATALOG_GENERATE_SYMBOLS = YES;
@@ -465,7 +479,7 @@
 				CLANG_WARN__DUPLICATE_METHOD_MATCH = YES;
 				CODE_SIGN_IDENTITY = "Apple Development";
 				COPY_PHASE_STRIP = NO;
-				CURRENT_PROJECT_VERSION = 1.1.2;
+				CURRENT_PROJECT_VERSION = 1.6.1;
 				DEAD_CODE_STRIPPING = YES;
 				DEBUG_INFORMATION_FORMAT = "dwarf-with-dsym";
 				ENABLE_HARDENED_RUNTIME = YES;
@@ -474,7 +488,12 @@
 				ENABLE_USER_SCRIPT_SANDBOXING = YES;
 				GCC_C_LANGUAGE_STANDARD = gnu11;
 				GCC_NO_COMMON_BLOCKS = YES;
-				GCC_PREPROCESSOR_DEFINITIONS = "$(inherited)";
+				GCC_PREPROCESSOR_DEFINITIONS = (
+					"$(inherited)",
+					"HAVE_LIBPNG=1",
+					"HAVE_TM_GMTOFF=1",
+					"HAVE_TIMEGM=1",
+				);
 				GCC_TREAT_IMPLICIT_FUNCTION_DECLARATIONS_AS_ERRORS = YES;
 				GCC_TREAT_INCOMPATIBLE_POINTER_TYPE_WARNINGS_AS_ERRORS = YES;
 				GCC_WARN_64_TO_32_BIT_CONVERSION = YES;
@@ -492,9 +511,20 @@
 				GCC_WARN_UNUSED_LABEL = YES;
 				GCC_WARN_UNUSED_PARAMETER = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
+				HEADER_SEARCH_PATHS = (
+					/usr/local/include,
+					/opt/local/include,
+					/opt/homebrew/include,
+				);
 				MACOSX_DEPLOYMENT_TARGET = 11.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
+				OTHER_LDFLAGS = (
+					"-L/usr/local/lib",
+					"-L/opt/local/lib",
+					"-L/opt/homebrew/lib",
+					"-lpng16",
+				);
 				RUN_CLANG_STATIC_ANALYZER = YES;
 				SDKROOT = macosx;
 				STRING_CATALOG_GENERATE_SYMBOLS = YES;
diff --git a/testpdfio.c b/testpdfio.c
index 8726643..4916366 100644
--- a/testpdfio.c
+++ b/testpdfio.c
@@ -3486,7 +3486,7 @@ write_pdfa_file(
 
   // Embed a base font, which are not allowed for PDF/A
   testBegin("pdfioFileCreateFontObjFromBase(Helvetica)");
-  if ((font = pdfioFileCreateFontObjFromBase(pdf, "Helvetica")) != NULL)
+  if (pdfioFileCreateFontObjFromBase(pdf, "Helvetica") != NULL)
   {
     testEnd(false);
     goto done;