diff --git a/dlls/msvcirt/msvcirt.c b/dlls/msvcirt/msvcirt.c
index fd721b5c870..6cc8f1c79a4 100644
--- a/dlls/msvcirt/msvcirt.c
+++ b/dlls/msvcirt/msvcirt.c
@@ -4032,6 +4032,41 @@ iostream* __thiscall iostream_scalar_dtor(ios *base, unsigned int flags)
     return this;
 }
 
+/* ??0Iostream_init@@QAE@AAVios@@H@Z */
+/* ??0Iostream_init@@QEAA@AEAVios@@H@Z */
+DEFINE_THISCALL_WRAPPER(Iostream_init_ios_ctor, 12)
+void* __thiscall Iostream_init_ios_ctor(void *this, ios *obj, int n)
+{
+    FIXME("(%p %p %d) stub\n", this, obj, n);
+    return this;
+}
+
+/* ??0Iostream_init@@QAE@XZ */
+/* ??0Iostream_init@@QEAA@XZ */
+DEFINE_THISCALL_WRAPPER(Iostream_init_ctor, 4)
+void* __thiscall Iostream_init_ctor(void *this)
+{
+    TRACE("(%p)\n", this);
+    return this;
+}
+
+/* ??1Iostream_init@@QAE@XZ */
+/* ??1Iostream_init@@QEAA@XZ */
+DEFINE_THISCALL_WRAPPER(Iostream_init_dtor, 4)
+void __thiscall Iostream_init_dtor(void *this)
+{
+    TRACE("(%p)\n", this);
+}
+
+/* ??4Iostream_init@@QAEAAV0@ABV0@@Z */
+/* ??4Iostream_init@@QEAAAEAV0@AEBV0@@Z */
+DEFINE_THISCALL_WRAPPER(Iostream_init_assign, 8)
+void* __thiscall Iostream_init_assign(void *this, const void *rhs)
+{
+    TRACE("(%p %p)\n", this, rhs);
+    return this;
+}
+
 /******************************************************************
  *		 ??0ostrstream@@QAE@XZ (MSVCRTI.@)
  */
diff --git a/dlls/msvcirt/msvcirt.spec b/dlls/msvcirt/msvcirt.spec
index 8361896d7ee..7b67bc7712d 100644
--- a/dlls/msvcirt/msvcirt.spec
+++ b/dlls/msvcirt/msvcirt.spec
@@ -1,7 +1,7 @@
-@ stub -arch=win32 ??0Iostream_init@@QAE@AAVios@@H@Z  # __thiscall Iostream_init::Iostream_init(class ios &,int)
-@ stub -arch=win64 ??0Iostream_init@@QEAA@AEAVios@@H@Z
-@ stub -arch=win32 ??0Iostream_init@@QAE@XZ  # __thiscall Iostream_init::Iostream_init(void)
-@ stub -arch=win64 ??0Iostream_init@@QEAA@XZ
+@ thiscall -arch=win32 ??0Iostream_init@@QAE@AAVios@@H@Z(ptr ptr long) Iostream_init_ios_ctor
+@ cdecl -arch=win64 ??0Iostream_init@@QEAA@AEAVios@@H@Z(ptr ptr long) Iostream_init_ios_ctor
+@ thiscall -arch=win32 ??0Iostream_init@@QAE@XZ(ptr) Iostream_init_ctor
+@ cdecl -arch=win64 ??0Iostream_init@@QEAA@XZ(ptr) Iostream_init_ctor
 @ thiscall -arch=i386 ??0exception@@QAE@ABQBD@Z(ptr ptr) MSVCP_exception_ctor
 @ cdecl -arch=win64 ??0exception@@QEAA@AEBQEBD@Z(ptr ptr) MSVCP_exception_ctor
 @ thiscall -arch=i386 ??0exception@@QAE@ABV0@@Z(ptr ptr) MSVCP_exception_copy_ctor
@@ -130,8 +130,8 @@
 @ cdecl -arch=win64 ??0strstreambuf@@QEAA@PEAEH0@Z(ptr ptr long ptr) strstreambuf_ubuffer_ctor
 @ thiscall -arch=win32 ??0strstreambuf@@QAE@XZ(ptr) strstreambuf_ctor
 @ cdecl -arch=win64 ??0strstreambuf@@QEAA@XZ(ptr) strstreambuf_ctor
-@ stub -arch=win32 ??1Iostream_init@@QAE@XZ  # __thiscall Iostream_init::~Iostream_init(void)
-@ stub -arch=win64 ??1Iostream_init@@QEAA@XZ
+@ thiscall -arch=win32 ??1Iostream_init@@QAE@XZ(ptr) Iostream_init_dtor
+@ cdecl -arch=win64 ??1Iostream_init@@QEAA@XZ(ptr) Iostream_init_dtor
 @ thiscall -arch=i386 ??1exception@@UAE@XZ(ptr) MSVCP_exception_dtor
 @ cdecl -arch=win64 ??1exception@@UEAA@XZ(ptr) MSVCP_exception_dtor
 @ thiscall -arch=win32 ??1filebuf@@UAE@XZ(ptr) filebuf_dtor
@@ -170,8 +170,8 @@
 @ stub -arch=win64 ??1strstream@@UEAA@XZ
 @ thiscall -arch=win32 ??1strstreambuf@@UAE@XZ(ptr) strstreambuf_dtor
 @ cdecl -arch=win64 ??1strstreambuf@@UEAA@XZ(ptr) strstreambuf_dtor
-@ stub -arch=win32 ??4Iostream_init@@QAEAAV0@ABV0@@Z  # class Iostream_init & __thiscall Iostream_init::operator=(class Iostream_init const &)
-@ stub -arch=win64 ??4Iostream_init@@QEAAAEAV0@AEBV0@@Z
+@ thiscall -arch=win32 ??4Iostream_init@@QAEAAV0@ABV0@@Z(ptr ptr) Iostream_init_assign
+@ cdecl -arch=win64 ??4Iostream_init@@QEAAAEAV0@AEBV0@@Z(ptr ptr) Iostream_init_assign
 @ thiscall -arch=i386 ??4exception@@QAEAAV0@ABV0@@Z(ptr ptr) MSVCP_exception_assign
 @ cdecl -arch=win64 ??4exception@@QEAAAEAV0@AEBV0@@Z(ptr ptr) MSVCP_exception_assign
 @ thiscall -arch=win32 ??4filebuf@@QAEAAV0@ABV0@@Z(ptr ptr) filebuf_assign
diff --git a/dlls/msvcrt20/msvcrt20.spec b/dlls/msvcrt20/msvcrt20.spec
index 86d11208b84..fad156bb170 100644
--- a/dlls/msvcrt20/msvcrt20.spec
+++ b/dlls/msvcrt20/msvcrt20.spec
@@ -1,7 +1,7 @@
-@ stub -arch=win32 ??0Iostream_init@@QAE@AAVios@@H@Z
-@ stub -arch=win64 ??0Iostream_init@@QEAA@AEAVios@@H@Z
-@ stub -arch=win32 ??0Iostream_init@@QAE@XZ
-@ stub -arch=win64 ??0Iostream_init@@QEAA@XZ
+@ thiscall -arch=win32 ??0Iostream_init@@QAE@AAVios@@H@Z(ptr ptr long) msvcirt.??0Iostream_init@@QAE@AAVios@@H@Z
+@ cdecl -arch=win64 ??0Iostream_init@@QEAA@AEAVios@@H@Z(ptr ptr long) msvcirt.??0Iostream_init@@QEAA@AEAVios@@H@Z
+@ thiscall -arch=win32 ??0Iostream_init@@QAE@XZ(ptr) msvcirt.??0Iostream_init@@QAE@XZ
+@ cdecl -arch=win64 ??0Iostream_init@@QEAA@XZ(ptr) msvcirt.??0Iostream_init@@QEAA@XZ
 @ thiscall -arch=win32 ??0filebuf@@QAE@ABV0@@Z(ptr ptr) msvcirt.??0filebuf@@QAE@ABV0@@Z
 @ cdecl -arch=win64 ??0filebuf@@QEAA@AEBV0@@Z(ptr ptr) msvcirt.??0filebuf@@QEAA@AEBV0@@Z
 @ thiscall -arch=win32 ??0filebuf@@QAE@H@Z(ptr long) msvcirt.??0filebuf@@QAE@H@Z
@@ -118,8 +118,8 @@
 @ cdecl -arch=win64 ??0strstreambuf@@QEAA@PEADH0@Z(ptr ptr long ptr) msvcirt.??0strstreambuf@@QEAA@PEADH0@Z
 @ thiscall -arch=win32 ??0strstreambuf@@QAE@XZ(ptr) msvcirt.??0strstreambuf@@QAE@XZ
 @ cdecl -arch=win64 ??0strstreambuf@@QEAA@XZ(ptr) msvcirt.??0strstreambuf@@QEAA@XZ
-@ stub -arch=win32 ??1Iostream_init@@QAE@XZ
-@ stub -arch=win64 ??1Iostream_init@@QEAA@XZ
+@ thiscall -arch=win32 ??1Iostream_init@@QAE@XZ(ptr) msvcirt.??1Iostream_init@@QAE@XZ
+@ cdecl -arch=win64 ??1Iostream_init@@QEAA@XZ(ptr) msvcirt.??1Iostream_init@@QEAA@XZ
 @ thiscall -arch=win32 ??1filebuf@@UAE@XZ(ptr) msvcirt.??1filebuf@@UAE@XZ
 @ cdecl -arch=win64 ??1filebuf@@UEAA@XZ(ptr) msvcirt.??1filebuf@@UEAA@XZ
 @ stub -arch=win32 ??1fstream@@UAE@XZ
@@ -158,8 +158,8 @@
 @ cdecl -arch=win64 ??2@YAPEAX_K@Z(long) msvcrt.??2@YAPEAX_K@Z
 @ cdecl -arch=win32 ??3@YAXPAX@Z(ptr) msvcrt.??3@YAXPAX@Z
 @ cdecl -arch=win64 ??3@YAXPEAX@Z(ptr) msvcrt.??3@YAXPEAX@Z
-@ stub -arch=win32 ??4Iostream_init@@QAEAAV0@ABV0@@Z
-@ stub -arch=win64 ??4Iostream_init@@QEAAAEAV0@AEBV0@@Z
+@ thiscall -arch=win32 ??4Iostream_init@@QAEAAV0@ABV0@@Z(ptr ptr) msvcirt.??4Iostream_init@@QAEAAV0@ABV0@@Z
+@ cdecl -arch=win64 ??4Iostream_init@@QEAAAEAV0@AEBV0@@Z(ptr ptr) msvcirt.??4Iostream_init@@QEAAAEAV0@AEBV0@@Z
 @ thiscall -arch=win32 ??4filebuf@@QAEAAV0@ABV0@@Z(ptr ptr) msvcirt.??4filebuf@@QAEAAV0@ABV0@@Z
 @ cdecl -arch=win64 ??4filebuf@@QEAAAEAV0@AEBV0@@Z(ptr ptr) msvcirt.??4filebuf@@QEAAAEAV0@AEBV0@@Z
 @ stub -arch=win32 ??4fstream@@QAEAAV0@AAV0@@Z
diff --git a/dlls/msvcrt40/msvcrt40.spec b/dlls/msvcrt40/msvcrt40.spec
index e78f085fab4..4ac328aa25e 100644
--- a/dlls/msvcrt40/msvcrt40.spec
+++ b/dlls/msvcrt40/msvcrt40.spec
@@ -1,7 +1,7 @@
-@ stub -arch=win32 ??0Iostream_init@@QAE@AAVios@@H@Z
-@ stub -arch=win64 ??0Iostream_init@@QEAA@AEAVios@@H@Z
-@ stub -arch=win32 ??0Iostream_init@@QAE@XZ
-@ stub -arch=win64 ??0Iostream_init@@QEAA@XZ
+@ thiscall -arch=win32 ??0Iostream_init@@QAE@AAVios@@H@Z(ptr ptr long) msvcirt.??0Iostream_init@@QAE@AAVios@@H@Z
+@ cdecl -arch=win64 ??0Iostream_init@@QEAA@AEAVios@@H@Z(ptr ptr long) msvcirt.??0Iostream_init@@QEAA@AEAVios@@H@Z
+@ thiscall -arch=win32 ??0Iostream_init@@QAE@XZ(ptr) msvcirt.??0Iostream_init@@QAE@XZ
+@ cdecl -arch=win64 ??0Iostream_init@@QEAA@XZ(ptr) msvcirt.??0Iostream_init@@QEAA@XZ
 @ thiscall -arch=i386 ??0__non_rtti_object@@QAE@ABV0@@Z(ptr ptr) msvcrt.??0__non_rtti_object@@QAE@ABV0@@Z
 @ cdecl -arch=win64 ??0__non_rtti_object@@QEAA@AEBV0@@Z(ptr ptr) msvcrt.??0__non_rtti_object@@QEAA@AEBV0@@Z
 @ thiscall -arch=i386 ??0__non_rtti_object@@QAE@PBD@Z(ptr ptr) msvcrt.??0__non_rtti_object@@QAE@PBD@Z
@@ -140,8 +140,8 @@
 @ cdecl -arch=win64 ??0strstreambuf@@QEAA@PEADH0@Z(ptr ptr long ptr) msvcirt.??0strstreambuf@@QEAA@PEADH0@Z
 @ thiscall -arch=win32 ??0strstreambuf@@QAE@XZ(ptr) msvcirt.??0strstreambuf@@QAE@XZ
 @ cdecl -arch=win64 ??0strstreambuf@@QEAA@XZ(ptr) msvcirt.??0strstreambuf@@QEAA@XZ
-@ stub -arch=win32 ??1Iostream_init@@QAE@XZ
-@ stub -arch=win64 ??1Iostream_init@@QEAA@XZ
+@ thiscall -arch=win32 ??1Iostream_init@@QAE@XZ(ptr) msvcirt.??1Iostream_init@@QAE@XZ
+@ cdecl -arch=win64 ??1Iostream_init@@QEAA@XZ(ptr) msvcirt.??1Iostream_init@@QEAA@XZ
 @ thiscall -arch=i386 ??1__non_rtti_object@@UAE@XZ(ptr) msvcrt.??1__non_rtti_object@@UAE@XZ
 @ cdecl -arch=win64 ??1__non_rtti_object@@UEAA@XZ(ptr) msvcrt.??1__non_rtti_object@@UEAA@XZ
 @ thiscall -arch=i386 ??1bad_cast@@UAE@XZ(ptr) msvcrt.??1bad_cast@@UAE@XZ
@@ -192,8 +192,8 @@
 @ cdecl -arch=win64 ??2@YAPEAX_K@Z(long) msvcrt.??2@YAPEAX_K@Z
 @ cdecl -arch=win32 ??3@YAXPAX@Z(ptr) msvcrt.??3@YAXPAX@Z
 @ cdecl -arch=win64 ??3@YAXPEAX@Z(ptr) msvcrt.??3@YAXPEAX@Z
-@ stub -arch=win32 ??4Iostream_init@@QAEAAV0@ABV0@@Z
-@ stub -arch=win64 ??4Iostream_init@@QEAAAEAV0@AEBV0@@Z
+@ thiscall -arch=win32 ??4Iostream_init@@QAEAAV0@ABV0@@Z(ptr ptr) msvcirt.??4Iostream_init@@QAEAAV0@ABV0@@Z
+@ cdecl -arch=win64 ??4Iostream_init@@QEAAAEAV0@AEBV0@@Z(ptr ptr) msvcirt.??4Iostream_init@@QEAAAEAV0@AEBV0@@Z
 @ thiscall -arch=i386 ??4__non_rtti_object@@QAEAAV0@ABV0@@Z(ptr ptr) msvcrt.??4__non_rtti_object@@QAEAAV0@ABV0@@Z
 @ cdecl -arch=win64 ??4__non_rtti_object@@QEAAAEAV0@AEBV0@@Z(ptr ptr) msvcrt.??4__non_rtti_object@@QEAAAEAV0@AEBV0@@Z
 @ thiscall -arch=i386 ??4bad_cast@@QAEAAV0@ABV0@@Z(ptr ptr) msvcrt.??4bad_cast@@QAEAAV0@ABV0@@Z