GUACAMOLE-407: Explicitly set LD_LIBRARY_PATH such that linker can find guacd's protocol plugins.
diff --git a/Dockerfile b/Dockerfile
index 120ba88..dc58765 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -85,6 +85,7 @@
 
 # Runtime environment
 ENV LC_ALL=en_US.UTF-8
+ENV LD_LIBRARY_PATH=${PREFIX_DIR}/lib
 ENV GUACD_LOG_LEVEL=info
 
 ARG RUNTIME_DEPENDENCIES="            \