diff --git a/mozilla/modules/libimg/png/pngread.c b/mozilla/modules/libimg/png/pngread.c
index bd7af8de1c1..12ffa495e89 100644
--- a/mozilla/modules/libimg/png/pngread.c
+++ b/mozilla/modules/libimg/png/pngread.c
@@ -56,7 +56,7 @@ png_create_read_struct(png_charp user_png_ver, png_voidp error_ptr,
    /* initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
    png_ptr->zbuf = png_malloc(png_ptr, png_ptr->zbuf_size);
-   memset(png_ptr->zbuf, NULL, png_ptr->zbuf_size );
+   memset(png_ptr->zbuf, 0, png_ptr->zbuf_size );
 
    png_ptr->zstream.zalloc = png_zalloc;
    png_ptr->zstream.zfree = png_zfree;
diff --git a/mozilla/modules/libimg/src/ipng.c b/mozilla/modules/libimg/src/ipng.c
index a705d52049f..e631c12b3cb 100644
--- a/mozilla/modules/libimg/src/ipng.c
+++ b/mozilla/modules/libimg/src/ipng.c
@@ -213,7 +213,7 @@ png_delay_time_callback(void *closure)
 
     XP_ASSERT(ipng_ptr->state == PNG_DELAY);
 
-    ipng_ptr->delay_time = NULL;
+    ipng_ptr->delay_time = 0;
 
     if (ipng_ptr->ic->state == IC_ABORT_PENDING)
         return;                                        
diff --git a/mozilla/modules/libpref/src/prefapi.c b/mozilla/modules/libpref/src/prefapi.c
index ed8804b8874..1ba4e8e7eab 100644
--- a/mozilla/modules/libpref/src/prefapi.c
+++ b/mozilla/modules/libpref/src/prefapi.c
@@ -1458,6 +1458,9 @@ static XP_Bool pref_ValueChanged(PrefValue oldValue, PrefValue newValue, PrefTyp
 		case PREF_BOOL:
 			changed = oldValue.boolVal != newValue.boolVal;
 			break;
+
+		default:
+			break;
 	}
 	return changed;
 }
@@ -2093,7 +2096,7 @@ void pref_Alert(char* msg)
 #if defined (XP_WIN)
 		MessageBox (NULL, msg, "Netscape -- JS Preference Warning", MB_OK);
 #elif defined(XP_OS2)
-      WinMessageBox (HWND_DESKTOP, NULL, msg, "Netscape -- JS Preference Warning", 0, MB_WARNING | MB_OK | MB_APPLMODAL | MB_MOVEABLE);
+      WinMessageBox (HWND_DESKTOP, 0, msg, "Netscape -- JS Preference Warning", 0, MB_WARNING | MB_OK | MB_APPLMODAL | MB_MOVEABLE);
 #endif
 }
 
diff --git a/mozilla/modules/libpref/src/prefapi.cpp b/mozilla/modules/libpref/src/prefapi.cpp
index ed8804b8874..1ba4e8e7eab 100644
--- a/mozilla/modules/libpref/src/prefapi.cpp
+++ b/mozilla/modules/libpref/src/prefapi.cpp
@@ -1458,6 +1458,9 @@ static XP_Bool pref_ValueChanged(PrefValue oldValue, PrefValue newValue, PrefTyp
 		case PREF_BOOL:
 			changed = oldValue.boolVal != newValue.boolVal;
 			break;
+
+		default:
+			break;
 	}
 	return changed;
 }
@@ -2093,7 +2096,7 @@ void pref_Alert(char* msg)
 #if defined (XP_WIN)
 		MessageBox (NULL, msg, "Netscape -- JS Preference Warning", MB_OK);
 #elif defined(XP_OS2)
-      WinMessageBox (HWND_DESKTOP, NULL, msg, "Netscape -- JS Preference Warning", 0, MB_WARNING | MB_OK | MB_APPLMODAL | MB_MOVEABLE);
+      WinMessageBox (HWND_DESKTOP, 0, msg, "Netscape -- JS Preference Warning", 0, MB_WARNING | MB_OK | MB_APPLMODAL | MB_MOVEABLE);
 #endif
 }