diff --git a/indra/llcommon/llapr.h b/indra/llcommon/llapr.h
index 034546c3f39f669e10566b80231cbb83a5596f68..752574c65ddd9d677214429b876cd9cf6cb56088 100755
--- a/indra/llcommon/llapr.h
+++ b/indra/llcommon/llapr.h
@@ -182,8 +182,10 @@ typedef LLAtomic32<S32> LLAtomicS32;
 // abbreviated flags
 #define LL_APR_R (APR_READ) // "r"
 #define LL_APR_W (APR_CREATE|APR_TRUNCATE|APR_WRITE) // "w"
+#define LL_APR_A (APR_CREATE|APR_WRITE|APR_APPEND) // "w"
 #define LL_APR_RB (APR_READ|APR_BINARY) // "rb"
 #define LL_APR_WB (APR_CREATE|APR_TRUNCATE|APR_WRITE|APR_BINARY) // "wb"
+#define LL_APR_AB (APR_CREATE|APR_WRITE|APR_BINARY|APR_APPEND)
 #define LL_APR_RPB (APR_READ|APR_WRITE|APR_BINARY) // "r+b"
 #define LL_APR_WPB (APR_CREATE|APR_TRUNCATE|APR_READ|APR_WRITE|APR_BINARY) // "w+b"
 
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index dcddd0fbf5f8008df844f18aa560fd1e387f638c..7f56d7afdd27cd52cb426c11b133b468c051d05c 100755
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -3522,7 +3522,7 @@ bool LLAppViewer::anotherInstanceRunning()
 	{
 		// File exists, try opening with write permissions
 		LLAPRFile outfile ;
-		outfile.open(marker_file, LL_APR_WB);
+		outfile.open(marker_file, LL_APR_AB);
 		apr_file_t* fMarker = outfile.getFileHandle() ; 
 		if (!fMarker)
 		{