diff --git a/src/backends/reference/backend.mk b/src/backends/reference/backend.mk
index d868069..b23c752 100644
--- a/src/backends/reference/backend.mk
+++ b/src/backends/reference/backend.mk
@@ -66,6 +66,7 @@
         workloads/ResizeBilinear.cpp \
         workloads/SpaceToBatchNd.cpp \
         workloads/StridedSlice.cpp \
+        workloads/StringMapping.cpp \
         workloads/Softmax.cpp
 
 # BACKEND_TEST_SOURCES contains the list of files to be included