diff --git a/dlls/mshtml/dispex.c b/dlls/mshtml/dispex.c
index 39630590228..6d248691d6b 100644
--- a/dlls/mshtml/dispex.c
+++ b/dlls/mshtml/dispex.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 #define NONAMELESSUNION
diff --git a/dlls/mshtml/htmlanchor.c b/dlls/mshtml/htmlanchor.c
index a0e96af822e..da48601fe87 100644
--- a/dlls/mshtml/htmlanchor.c
+++ b/dlls/mshtml/htmlanchor.c
@@ -18,7 +18,6 @@
 
 #include <stdarg.h>
 #include <stdio.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlarea.c b/dlls/mshtml/htmlarea.c
index a5ebfe757ae..a0708c4b062 100644
--- a/dlls/mshtml/htmlarea.c
+++ b/dlls/mshtml/htmlarea.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlattr.c b/dlls/mshtml/htmlattr.c
index 14b79812eb0..dc8c45e488a 100644
--- a/dlls/mshtml/htmlattr.c
+++ b/dlls/mshtml/htmlattr.c
@@ -18,7 +18,6 @@
 
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlbody.c b/dlls/mshtml/htmlbody.c
index 9955a8e6498..32c49fe1214 100644
--- a/dlls/mshtml/htmlbody.c
+++ b/dlls/mshtml/htmlbody.c
@@ -18,7 +18,6 @@
 
 #include <stdarg.h>
 #include <stdio.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlcurstyle.c b/dlls/mshtml/htmlcurstyle.c
index 85ac99aef92..2abe5df30ec 100644
--- a/dlls/mshtml/htmlcurstyle.c
+++ b/dlls/mshtml/htmlcurstyle.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmldoc.c b/dlls/mshtml/htmldoc.c
index 79241fc34cc..9faf987d7b9 100644
--- a/dlls/mshtml/htmldoc.c
+++ b/dlls/mshtml/htmldoc.c
@@ -18,7 +18,6 @@
 
 #include <stdarg.h>
 #include <stdio.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlelem.c b/dlls/mshtml/htmlelem.c
index 8187cbf867e..b9677ec867a 100644
--- a/dlls/mshtml/htmlelem.c
+++ b/dlls/mshtml/htmlelem.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 #include <math.h>
 
 #define COBJMACROS
diff --git a/dlls/mshtml/htmlelemcol.c b/dlls/mshtml/htmlelemcol.c
index f4722d96729..e72f21ffaa5 100644
--- a/dlls/mshtml/htmlelemcol.c
+++ b/dlls/mshtml/htmlelemcol.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlevent.c b/dlls/mshtml/htmlevent.c
index b3b95083f80..17f5fb35b71 100644
--- a/dlls/mshtml/htmlevent.c
+++ b/dlls/mshtml/htmlevent.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlform.c b/dlls/mshtml/htmlform.c
index 5906202f1c7..5d0928e4a9c 100644
--- a/dlls/mshtml/htmlform.c
+++ b/dlls/mshtml/htmlform.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlframe.c b/dlls/mshtml/htmlframe.c
index 972ddc80a50..7118ea86b57 100644
--- a/dlls/mshtml/htmlframe.c
+++ b/dlls/mshtml/htmlframe.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlimg.c b/dlls/mshtml/htmlimg.c
index 2dfd53eb0b9..f89e8e5ae84 100644
--- a/dlls/mshtml/htmlimg.c
+++ b/dlls/mshtml/htmlimg.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlinput.c b/dlls/mshtml/htmlinput.c
index 2ba5833f3c0..1a0a739d5d5 100644
--- a/dlls/mshtml/htmlinput.c
+++ b/dlls/mshtml/htmlinput.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 #include <limits.h>
 
 #define COBJMACROS
diff --git a/dlls/mshtml/htmllink.c b/dlls/mshtml/htmllink.c
index 22342027cbc..ddf67ca0f73 100644
--- a/dlls/mshtml/htmllink.c
+++ b/dlls/mshtml/htmllink.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlnode.c b/dlls/mshtml/htmlnode.c
index a2692b1a230..b5ff02bcee2 100644
--- a/dlls/mshtml/htmlnode.c
+++ b/dlls/mshtml/htmlnode.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlobject.c b/dlls/mshtml/htmlobject.c
index b71b0e7db6f..67025489751 100644
--- a/dlls/mshtml/htmlobject.c
+++ b/dlls/mshtml/htmlobject.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlscript.c b/dlls/mshtml/htmlscript.c
index 4d7997e31a6..9b7f95e3bb0 100644
--- a/dlls/mshtml/htmlscript.c
+++ b/dlls/mshtml/htmlscript.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlselect.c b/dlls/mshtml/htmlselect.c
index 301d9fa5dc3..ad801f8433b 100644
--- a/dlls/mshtml/htmlselect.c
+++ b/dlls/mshtml/htmlselect.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlstyle.c b/dlls/mshtml/htmlstyle.c
index c4bd3a84867..4ee81ba7e99 100644
--- a/dlls/mshtml/htmlstyle.c
+++ b/dlls/mshtml/htmlstyle.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 #include <math.h>
 
 #define COBJMACROS
diff --git a/dlls/mshtml/htmlstyleelem.c b/dlls/mshtml/htmlstyleelem.c
index 538e79f0b5e..d2a4a75fe90 100644
--- a/dlls/mshtml/htmlstyleelem.c
+++ b/dlls/mshtml/htmlstyleelem.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlstylesheet.c b/dlls/mshtml/htmlstylesheet.c
index 243aea2e618..4519b06155e 100644
--- a/dlls/mshtml/htmlstylesheet.c
+++ b/dlls/mshtml/htmlstylesheet.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmltable.c b/dlls/mshtml/htmltable.c
index ad74ad30966..178e9e52304 100644
--- a/dlls/mshtml/htmltable.c
+++ b/dlls/mshtml/htmltable.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmltextarea.c b/dlls/mshtml/htmltextarea.c
index fb8c3830862..57f33732a01 100644
--- a/dlls/mshtml/htmltextarea.c
+++ b/dlls/mshtml/htmltextarea.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmltextnode.c b/dlls/mshtml/htmltextnode.c
index c2e7f375ada..56a0572459a 100644
--- a/dlls/mshtml/htmltextnode.c
+++ b/dlls/mshtml/htmltextnode.c
@@ -18,7 +18,6 @@
 
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/htmlwindow.c b/dlls/mshtml/htmlwindow.c
index 0ca4cd6397e..4196d1f45ad 100644
--- a/dlls/mshtml/htmlwindow.c
+++ b/dlls/mshtml/htmlwindow.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/mshtml_private.h b/dlls/mshtml/mshtml_private.h
index 7bc645e549f..e3486aa3314 100644
--- a/dlls/mshtml/mshtml_private.h
+++ b/dlls/mshtml/mshtml_private.h
@@ -40,6 +40,8 @@
 
 #include "nsiface.h"
 
+#include <assert.h>
+
 #define NS_ERROR_GENERATE_FAILURE(module,code) \
     ((nsresult) (((UINT32)(1u<<31)) | ((UINT32)(module+0x45)<<16) | ((UINT32)(code))))
 #define NS_ERROR_GENERATE_SUCCESS(module,code) \
diff --git a/dlls/mshtml/mutation.c b/dlls/mshtml/mutation.c
index 247a3277927..abe403ea976 100644
--- a/dlls/mshtml/mutation.c
+++ b/dlls/mshtml/mutation.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/navigate.c b/dlls/mshtml/navigate.c
index 233f58c89fd..8cbe0ec9304 100644
--- a/dlls/mshtml/navigate.c
+++ b/dlls/mshtml/navigate.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 #define NONAMELESSUNION
diff --git a/dlls/mshtml/nsembed.c b/dlls/mshtml/nsembed.c
index d4fe7e96fc2..ae94f224fac 100644
--- a/dlls/mshtml/nsembed.c
+++ b/dlls/mshtml/nsembed.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/nsevents.c b/dlls/mshtml/nsevents.c
index b060ae521c5..21908b09563 100644
--- a/dlls/mshtml/nsevents.c
+++ b/dlls/mshtml/nsevents.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/nsio.c b/dlls/mshtml/nsio.c
index ea8eae2007d..abf05aaa41b 100644
--- a/dlls/mshtml/nsio.c
+++ b/dlls/mshtml/nsio.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/oleobj.c b/dlls/mshtml/oleobj.c
index fb3ff8a8b73..c7ce641a949 100644
--- a/dlls/mshtml/oleobj.c
+++ b/dlls/mshtml/oleobj.c
@@ -18,7 +18,6 @@
 
 #include <stdarg.h>
 #include <stdio.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/omnavigator.c b/dlls/mshtml/omnavigator.c
index 43067b813a1..a8f829b6a57 100644
--- a/dlls/mshtml/omnavigator.c
+++ b/dlls/mshtml/omnavigator.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/pluginhost.c b/dlls/mshtml/pluginhost.c
index d880cc89a9d..ad67db5548c 100644
--- a/dlls/mshtml/pluginhost.c
+++ b/dlls/mshtml/pluginhost.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/range.c b/dlls/mshtml/range.c
index 8c802ee9ede..89f68046a33 100644
--- a/dlls/mshtml/range.c
+++ b/dlls/mshtml/range.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/script.c b/dlls/mshtml/script.c
index 8f7f502e121..28e07a50c8e 100644
--- a/dlls/mshtml/script.c
+++ b/dlls/mshtml/script.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/secmgr.c b/dlls/mshtml/secmgr.c
index 019327caa47..a72099f33b9 100644
--- a/dlls/mshtml/secmgr.c
+++ b/dlls/mshtml/secmgr.c
@@ -18,7 +18,6 @@
 
 #include <stdarg.h>
 #include <stdio.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/svg.c b/dlls/mshtml/svg.c
index e1de57fc4b1..75036cb39d6 100644
--- a/dlls/mshtml/svg.c
+++ b/dlls/mshtml/svg.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 #include <math.h>
 
 #define COBJMACROS
diff --git a/dlls/mshtml/task.c b/dlls/mshtml/task.c
index 28cb88ab5f1..67b7633a5b4 100644
--- a/dlls/mshtml/task.c
+++ b/dlls/mshtml/task.c
@@ -18,7 +18,6 @@
 
 #include <stdarg.h>
 #include <stdio.h>
-#include <assert.h>
 
 #define COBJMACROS
 
diff --git a/dlls/mshtml/xmlhttprequest.c b/dlls/mshtml/xmlhttprequest.c
index 814162acbbc..d7d8ce51593 100644
--- a/dlls/mshtml/xmlhttprequest.c
+++ b/dlls/mshtml/xmlhttprequest.c
@@ -17,7 +17,6 @@
  */
 
 #include <stdarg.h>
-#include <assert.h>
 
 #define COBJMACROS