diff --git a/renderdoc/core/core.cpp b/renderdoc/core/core.cpp
index ae9fc7820..9d2c68496 100644
--- a/renderdoc/core/core.cpp
+++ b/renderdoc/core/core.cpp
@@ -735,6 +735,7 @@ Serialiser *RenderDoc::OpenWriteSerialiser(uint32_t frameNum, RDCInitParams *par
           }) != m_Captures.end())
     {
       m_CurrentLogFile = StringFormat::Fmt("%s_frame%u_%d.rdc", m_LogFile.c_str(), frameNum, altnum);
+      altnum++;
     }
   }