diff --git a/compiler-rt/lib/profile/InstrProfilingFile.c b/compiler-rt/lib/profile/InstrProfilingFile.c
index 35a3b48..4fc7693 100644
--- a/compiler-rt/lib/profile/InstrProfilingFile.c
+++ b/compiler-rt/lib/profile/InstrProfilingFile.c
@@ -46,7 +46,7 @@
     return -1;
 
   /* Append to the file to support profiling multiple shared objects. */
-  OutputFile = fopen(OutputName, "a");
+  OutputFile = fopen(OutputName, "ab");
   if (!OutputFile)
     return -1;