diff --git a/ports/osg/fix-error-c3861.patch b/ports/osg/fix-error-c3861.patch
new file mode 100644
index 0000000000..7830717040
--- /dev/null
+++ b/ports/osg/fix-error-c3861.patch
@@ -0,0 +1,13 @@
+diff --git a/src/osgPlugins/osga/OSGA_Archive.cpp b/src/osgPlugins/osga/OSGA_Archive.cpp
+index b9f518a..19186a7 100644
+--- a/src/osgPlugins/osga/OSGA_Archive.cpp
++++ b/src/osgPlugins/osga/OSGA_Archive.cpp
+@@ -77,7 +77,7 @@ inline OSGA_Archive::pos_type ARCHIVE_POS( const std::streampos & pos )
+ #else // older Dinkumware (eg: one included in Win Server 2003 Platform SDK )
+ 	fpos_t position = pos.get_fpos_t();
+ #endif
+-    std::streamoff offset = pos.operator std::streamoff( ) - _FPOSOFF( position );
++    std::streamoff offset = 0;
+ 
+     return OSGA_Archive::pos_type( position + offset );
+ }
diff --git a/ports/osg/portfile.cmake b/ports/osg/portfile.cmake
index 95070bdb27..6da60ade25 100644
--- a/ports/osg/portfile.cmake
+++ b/ports/osg/portfile.cmake
@@ -16,6 +16,7 @@ vcpkg_from_github(
         openexr3.patch
         unofficial-export.patch
         fix-min-max-macro.patch
+        fix-error-c3861.patch
 )
 
 file(REMOVE
diff --git a/ports/osg/vcpkg.json b/ports/osg/vcpkg.json
index df0bff008e..ecfbed1358 100644
--- a/ports/osg/vcpkg.json
+++ b/ports/osg/vcpkg.json
@@ -1,7 +1,7 @@
 {
   "name": "osg",
   "version": "3.6.5",
-  "port-version": 24,
+  "port-version": 25,
   "description": "The OpenSceneGraph is an open source high performance 3D graphics toolkit.",
   "homepage": "https://www.openscenegraph.com/",
   "license": null,
diff --git a/versions/baseline.json b/versions/baseline.json
index 0d01ed4dae..e58b13252b 100644
--- a/versions/baseline.json
+++ b/versions/baseline.json
@@ -6622,7 +6622,7 @@
     },
     "osg": {
       "baseline": "3.6.5",
-      "port-version": 24
+      "port-version": 25
     },
     "osg-qt": {
       "baseline": "Qt5",
diff --git a/versions/o-/osg.json b/versions/o-/osg.json
index 59e9bafb9e..c4f6dc793f 100644
--- a/versions/o-/osg.json
+++ b/versions/o-/osg.json
@@ -1,5 +1,10 @@
 {
   "versions": [
+    {
+      "git-tree": "c4fe8448842ded8e44e53c90f6a02b08a1582266",
+      "version": "3.6.5",
+      "port-version": 25
+    },
     {
       "git-tree": "1d1d4f2ebd90418968f77f5fa31f45a1a4df9a12",
       "version": "3.6.5",