diff --git a/direct/src/dist/FreezeTool.py b/direct/src/dist/FreezeTool.py
index 13c77bc7fc..fa00282cc8 100644
--- a/direct/src/dist/FreezeTool.py
+++ b/direct/src/dist/FreezeTool.py
@@ -1207,13 +1207,16 @@ class Freezer:
                         except ImportError:
                             pass
                 else:
-                    self.__loadModule(self.ModuleDef(modname, implicit = True))
+                    try:
+                        self.__loadModule(self.ModuleDef(modname, implicit = True))
+                    except ImportError:
+                        pass
 
         # Special case for sysconfig, which depends on a platform-specific
         # sysconfigdata module on POSIX systems.
         missing = []
         if 'sysconfig' in self.mf.modules and \
-           ('linux' in self.platform or 'mac' in self.platform):
+           ('linux' in self.platform or 'mac' in self.platform or 'emscripten' in self.platform):
             modname = '_sysconfigdata'
             if sys.version_info >= (3, 6):
                 modname += '_'
@@ -1225,6 +1228,12 @@ class Freezer:
                     modname += '_linux_' + arch + '-linux-gnu'
                 elif 'mac' in self.platform:
                     modname += '_darwin_darwin'
+                elif 'emscripten' in self.platform:
+                    if '_' in self.platform:
+                        arch = self.platform.split('_', 1)[1]
+                    else:
+                        arch = 'wasm32'
+                    modname += '_emscripten_' + arch + '-emscripten'
 
             try:
                 self.__loadModule(self.ModuleDef(modname, implicit=True))
diff --git a/panda/src/pnmimagetypes/pnmFileTypePNG.cxx b/panda/src/pnmimagetypes/pnmFileTypePNG.cxx
index 5f43ddd6ff..afb7dc1de2 100644
--- a/panda/src/pnmimagetypes/pnmFileTypePNG.cxx
+++ b/panda/src/pnmimagetypes/pnmFileTypePNG.cxx
@@ -451,8 +451,8 @@ png_read_data(png_structp png_ptr, png_bytep data, png_size_t length) {
  * This is our own warning handler.  It is called by the png library to issue
  * a warning message.
  */
-void PNMFileTypePNG::Reader::
-png_warning(png_structp, png_const_charp warning_msg) {
+void (PNMFileTypePNG::Reader::
+png_warning)(png_structp, png_const_charp warning_msg) {
   pnmimage_png_cat.warning()
     << warning_msg << "\n";
 }
@@ -461,8 +461,8 @@ png_warning(png_structp, png_const_charp warning_msg) {
  * This is our own error handler.  It is called by the png library to issue a
  * fatal error message.
  */
-void PNMFileTypePNG::Reader::
-png_error(png_structp png_ptr, png_const_charp error_msg) {
+void (PNMFileTypePNG::Reader::
+png_error)(png_structp png_ptr, png_const_charp error_msg) {
   pnmimage_png_cat.error()
     << error_msg << "\n";
 
@@ -921,8 +921,8 @@ png_flush_data(png_structp png_ptr) {
  * This is our own warning handler.  It is called by the png library to issue
  * a warning message.
  */
-void PNMFileTypePNG::Writer::
-png_warning(png_structp, png_const_charp warning_msg) {
+void (PNMFileTypePNG::Writer::
+png_warning)(png_structp, png_const_charp warning_msg) {
   pnmimage_png_cat.warning()
     << warning_msg << "\n";
 }
@@ -931,8 +931,8 @@ png_warning(png_structp, png_const_charp warning_msg) {
  * This is our own error handler.  It is called by the png library to issue a
  * fatal error message.
  */
-void PNMFileTypePNG::Writer::
-png_error(png_structp png_ptr, png_const_charp error_msg) {
+void (PNMFileTypePNG::Writer::
+png_error)(png_structp png_ptr, png_const_charp error_msg) {
   pnmimage_png_cat.error()
     << error_msg << "\n";
 
diff --git a/panda/src/pnmimagetypes/pnmFileTypePNG.h b/panda/src/pnmimagetypes/pnmFileTypePNG.h
index 535a5b2f43..8ed2b817e4 100644
--- a/panda/src/pnmimagetypes/pnmFileTypePNG.h
+++ b/panda/src/pnmimagetypes/pnmFileTypePNG.h
@@ -58,8 +58,8 @@ public:
     static void png_read_data(png_structp png_ptr, png_bytep data,
                               png_size_t length);
 
-    static void png_error(png_structp png_ptr, png_const_charp error_msg);
-    static void png_warning(png_structp png_ptr, png_const_charp warning_msg);
+    static void (png_error)(png_structp png_ptr, png_const_charp error_msg);
+    static void (png_warning)(png_structp png_ptr, png_const_charp warning_msg);
 
     png_structp _png;
     png_infop _info;
@@ -84,8 +84,8 @@ public:
                                png_size_t length);
     static void png_flush_data(png_structp png_ptr);
 
-    static void png_error(png_structp png_ptr, png_const_charp error_msg);
-    static void png_warning(png_structp png_ptr, png_const_charp warning_msg);
+    static void (png_error)(png_structp png_ptr, png_const_charp error_msg);
+    static void (png_warning)(png_structp png_ptr, png_const_charp warning_msg);
 
     png_structp _png;
     png_infop _info;