diff --git a/dlls/quartz/acmwrapper.c b/dlls/quartz/acmwrapper.c
index 2b2588088c9..62f00203d5b 100644
--- a/dlls/quartz/acmwrapper.c
+++ b/dlls/quartz/acmwrapper.c
@@ -234,7 +234,7 @@ static HRESULT ACMWrapper_Cleanup(TransformFilterImpl* pTransformFilter)
     return S_OK;
 }
 
-TransformFuncsTable ACMWrapper_FuncsTable = {
+static const TransformFuncsTable ACMWrapper_FuncsTable = {
     NULL,
     ACMWrapper_ProcessSampleData,
     NULL,
diff --git a/dlls/quartz/avidec.c b/dlls/quartz/avidec.c
index c4f8c540714..a87850053ae 100644
--- a/dlls/quartz/avidec.c
+++ b/dlls/quartz/avidec.c
@@ -257,7 +257,7 @@ static HRESULT AVIDec_Cleanup(TransformFilterImpl* pTransformFilter)
     return S_OK;
 }
 
-TransformFuncsTable AVIDec_FuncsTable = {
+static const TransformFuncsTable AVIDec_FuncsTable = {
     AVIDec_ProcessBegin,
     AVIDec_ProcessSampleData,
     AVIDec_ProcessEnd,
diff --git a/dlls/quartz/main.c b/dlls/quartz/main.c
index def4598f835..b5e403280d0 100644
--- a/dlls/quartz/main.c
+++ b/dlls/quartz/main.c
@@ -209,7 +209,7 @@ HRESULT WINAPI DllCanUnloadNow()
 #define OUR_GUID_ENTRY(name, l, w1, w2, b1, b2, b3, b4, b5, b6, b7, b8) \
     { { l, w1, w2, { b1, b2,  b3,  b4,  b5,  b6,  b7,  b8 } } , #name },
 
-static struct {
+static const struct {
 	const GUID	riid;
 	const char 	*name;
 } InterfaceDesc[] =
diff --git a/dlls/quartz/transform.c b/dlls/quartz/transform.c
index 63b6ad512b0..59c2e3aadaf 100644
--- a/dlls/quartz/transform.c
+++ b/dlls/quartz/transform.c
@@ -173,7 +173,7 @@ static HRESULT TransformFilter_OutputPin_Construct(const PIN_INFO * pPinInfo, AL
     return E_FAIL;
 }
 
-HRESULT TransformFilter_Create(TransformFilterImpl* pTransformFilter, const CLSID* pClsid, TransformFuncsTable* pFuncsTable)
+HRESULT TransformFilter_Create(TransformFilterImpl* pTransformFilter, const CLSID* pClsid, const TransformFuncsTable* pFuncsTable)
 {
     HRESULT hr;
     PIN_INFO piInput;
diff --git a/dlls/quartz/transform.h b/dlls/quartz/transform.h
index f29ee6776ec..65adad0c139 100644
--- a/dlls/quartz/transform.h
+++ b/dlls/quartz/transform.h
@@ -42,7 +42,7 @@ struct TransformFilterImpl
 
     IPin ** ppPins;
 
-    TransformFuncsTable * pFuncsTable;
+    const TransformFuncsTable * pFuncsTable;
 };
 
-HRESULT TransformFilter_Create(TransformFilterImpl*, const CLSID*, TransformFuncsTable* pFuncsTable);
+HRESULT TransformFilter_Create(TransformFilterImpl*, const CLSID*, const TransformFuncsTable* pFuncsTable);