diff --git a/Android.mk b/Android.mk
index 2a6eb43..4e92908 100644
--- a/Android.mk
+++ b/Android.mk
@@ -22,9 +22,18 @@
 	pngwtran.c \
 	pngwutil.c
 
-common_CFLAGS := ## -fomit-frame-pointer
+common_CFLAGS := -fvisibility=hidden ## -fomit-frame-pointer
 
-common_C_INCLUDES += \
+ifeq ($(HOST_OS),windows)
+  ifeq ($(USE_MINGW),)
+    # Case where we're building windows but not under linux (so it must be cygwin)
+    # In this case, gcc cygwin doesn't recognize -fvisibility=hidden
+    $(info libpng: Ignoring gcc flag $(common_CFLAGS) on Cygwin)
+    common_CFLAGS := 
+  endif
+endif
+
+common_C_INCLUDES += 
 
 common_COPY_HEADERS_TO := libpng
 common_COPY_HEADERS := png.h pngconf.h pngusr.h
diff --git a/pngconf.h b/pngconf.h
index 82c6008..219b42e 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1509,7 +1509,11 @@
 #  define PNGAPI
 #endif
 #ifndef PNG_IMPEXP
-#  define PNG_IMPEXP
+#  if ((__GNUC__-0) * 10 + __GNUC_MINOR__-0 >= 33)
+#    define PNG_IMPEXP  __attribute__((visibility ("default")))
+#  else
+#    define PNG_IMPEXP
+#  endif
 #endif
 
 #ifdef PNG_BUILDSYMS
diff --git a/pngread.c b/pngread.c
index fc4788b..b301d41 100644
--- a/pngread.c
+++ b/pngread.c
@@ -776,13 +776,18 @@
          png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
          break;
       }
-      if (ret != Z_OK)
+      if (ret != Z_OK) {
 #ifdef PNG_INDEX_SUPPORTED
-         if (png_ptr->index && png_ptr->row_number != png_ptr->height - 1)
+         if (png_ptr->index) {
+            if (png_ptr->row_number != png_ptr->height - 1) {
+               png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
+                     "Decompression error");
+            }
+         } else
 #endif
             png_error(png_ptr, png_ptr->zstream.msg ? png_ptr->zstream.msg :
-                   "Decompression error");
-
+                  "Decompression error");
+      }
    } while (png_ptr->zstream.avail_out);
 
    png_ptr->row_info.color_type = png_ptr->color_type;