diff --git a/libcopybit/copybit.cpp b/libcopybit/copybit.cpp
index 5d8da05..47d9b93 100644
--- a/libcopybit/copybit.cpp
+++ b/libcopybit/copybit.cpp
@@ -714,6 +714,10 @@
     ctx->mAlpha = MDP_ALPHA_NOP;
     ctx->mFlags = 0;
     ctx->sync.flags = 0;
+    ctx->relFence = -1;
+    for (int i=0; i < MDP_MAX_FENCE_FD; i++) {
+        ctx->acqFence[i] = -1;
+    }
     ctx->sync.acq_fen_fd = ctx->acqFence;
     ctx->sync.rel_fen_fd = &ctx->relFence;
     ctx->list.count = 0;