diff --git a/Makefile b/Makefile
index 6dcfe40c25..0fb5ffa128 100644
--- a/Makefile
+++ b/Makefile
@@ -305,6 +305,15 @@ then
   exit 1
 fi
 
+# Container tests needing locale data should install them in-container.
+# Other tests/binaries need to use locale data from the build tree.
+if [ "$$CONTAINER" = false ]
+then
+  ENVVARS="GCONV_PATH=$${BUILD_DIR}/iconvdata $$ENVVARS"
+  ENVVARS="LOCPATH=$${BUILD_DIR}/localedata $$ENVVARS"
+  ENVVARS="LC_ALL=C $$ENVVARS"
+fi
+
 # Expand environment setup command
 if [ -v ENVVARS ]
 then