diff --git a/CMakeLists.txt b/CMakeLists.txt
index 162d63a8d1..abaf0c7367 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -536,6 +536,8 @@ if(PNG_TESTS AND PNG_SHARED)
   list(SORT PNGSUITE_PNGS)
   file(GLOB TEST_PNGS "${CMAKE_CURRENT_SOURCE_DIR}/contrib/testpngs/*.png")
   list(SORT TEST_PNGS)
+  file(GLOB TEST_APNG_PNGS "${CMAKE_CURRENT_SOURCE_DIR}/contrib/testpngs/apng/*.png")
+  list(SORT TEST_APNG_PNGS)
   file(GLOB TEST_PNG3_PNGS "${CMAKE_CURRENT_SOURCE_DIR}/contrib/testpngs/png-3/*.png")
   list(SORT TEST_PNG3_PNGS)
 
@@ -555,6 +557,11 @@ if(PNG_TESTS AND PNG_SHARED)
                COMMAND pngtest
                FILES "${TEST_PNG3_PNGS}")
 
+  png_add_test(NAME pngtest-apng
+               COMMAND pngtest
+               OPTIONS --relaxed
+               FILES "${TEST_APNG_PNGS}")
+
   # pnggetset test:
   # Getter-to-setter roundtrips for various chunk types.
   add_executable(pnggetset ${pnggetset_sources})
diff --git a/contrib/testpngs/apng/frame-size-change.png b/contrib/testpngs/apng/frame-size-change.png
new file mode 100644
index 0000000000..06f03c17ca
Binary files /dev/null and b/contrib/testpngs/apng/frame-size-change.png differ
diff --git a/pngwutil.c b/pngwutil.c
index dae8850feb..823ee581fb 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -2886,6 +2886,21 @@ png_write_reset(png_struct *png_ptr)
    png_ptr->row_number = 0;
    png_ptr->pass = 0;
    png_ptr->mode &= ~PNG_HAVE_IDAT;
+
+   /* APNG frames may have different dimensions, so the row and filter
+    * buffers are frame-local and must be recreated for each new frame.
+    */
+   png_free(png_ptr, png_ptr->row_buf);
+   png_ptr->row_buf = NULL;
+
+#ifdef PNG_WRITE_FILTER_SUPPORTED
+   png_free(png_ptr, png_ptr->prev_row);
+   png_free(png_ptr, png_ptr->try_row);
+   png_free(png_ptr, png_ptr->tst_row);
+   png_ptr->prev_row = NULL;
+   png_ptr->try_row = NULL;
+   png_ptr->tst_row = NULL;
+#endif
 }
 
 void /* PRIVATE */
diff --git a/tests/pngtest-all b/tests/pngtest-all
index 6696ff52b7..418916504a 100755
--- a/tests/pngtest-all
+++ b/tests/pngtest-all
@@ -40,6 +40,9 @@ TEST --strict "${srcdir}"/pngtest.png
 # PNG-3 tests
 TEST --strict "${srcdir}"/contrib/testpngs/png-3/*.png
 
+# APNG tests
+TEST --relaxed "${srcdir}"/contrib/testpngs/apng/*.png
+
 # Various crashers
 # Use --relaxed because some come from fuzzers that don't maintain CRCs
 TEST --relaxed "${srcdir}"/contrib/testpngs/crashers/badcrc.png