diff --git a/ebml/EbmlElement.h b/ebml/EbmlElement.h
index 06fa39b..62ed7c5 100644
--- a/ebml/EbmlElement.h
+++ b/ebml/EbmlElement.h
@@ -238,6 +238,10 @@ extern const EbmlSemanticContext Context_EbmlGlobal;
 #define EBML_CTX_IDX_INFO(c,i) (c).MyTable[(i)].GetCallbacks
 #endif
 
+#if !defined(INVALID_FILEPOS_T)
+#define INVALID_FILEPOS_T 0
+#endif
+
 #define EBML_DEF_CONS
 #define EBML_DEF_SEP
 #define EBML_DEF_PARAM
diff --git a/src/EbmlVoid.cpp b/src/EbmlVoid.cpp
index 28564bf..60354d1 100644
--- a/src/EbmlVoid.cpp
+++ b/src/EbmlVoid.cpp
@@ -65,11 +65,11 @@ uint64 EbmlVoid::ReplaceWith(EbmlElement & EltToReplaceWith, IOCallback & output
 	EltToReplaceWith.UpdateSize(bKeepIntact);
 	if (HeadSize() + GetSize() < EltToReplaceWith.GetSize() + EltToReplaceWith.HeadSize()) {
 		// the element can't be written here !
-		return 0;
+		return INVALID_FILEPOS_T;
 	}
 	if (HeadSize() + GetSize() - EltToReplaceWith.GetSize() - EltToReplaceWith.HeadSize() == 1) {
 		// there is not enough space to put a filling element
-		return 0;
+		return INVALID_FILEPOS_T;
 	}
 
 	uint64 CurrentPosition = output.getFilePointer();