diff --git a/cmake/Rust.cmake b/cmake/Rust.cmake
index b3fcf23e9..3f29464aa 100644
--- a/cmake/Rust.cmake
+++ b/cmake/Rust.cmake
@@ -54,7 +54,7 @@ file(REAL_PATH "${CMAKE_BINARY_DIR}" fish_binary_dir)
 string(JOIN "," CURSES_LIBRARY_LIST ${CURSES_LIBRARY} ${CURSES_EXTRA_LIBRARY})
 
 # Tell Cargo where our build directory is so it can find config.h.
-corrosion_set_env_vars(${fish_rust_target}
+set(VARS_FOR_CARGO
     "FISH_BUILD_DIR=${fish_binary_dir}"
     "PREFIX=${CMAKE_INSTALL_PREFIX}"
     # Temporary hack to propogate CMake flags/options to build.rs.
@@ -66,3 +66,5 @@ corrosion_set_env_vars(${fish_rust_target}
     "LOCALEDIR=${CMAKE_INSTALL_FULL_LOCALEDIR}"
     "CURSES_LIBRARY_LIST=${CURSES_LIBRARY_LIST}"
 )
+
+corrosion_set_env_vars(${fish_rust_target} ${VARS_FOR_CARGO})
diff --git a/cmake/Tests.cmake b/cmake/Tests.cmake
index a416ce3b3..885cf367d 100644
--- a/cmake/Tests.cmake
+++ b/cmake/Tests.cmake
@@ -163,7 +163,7 @@ endif()
 if(NOT DEFINED ASAN)
     add_test(
         NAME "cargo-test"
-        COMMAND cargo test ${CARGO_FLAGS} --package fish-rust --target-dir target ${cargo_target_opt}
+        COMMAND env ${VARS_FOR_CARGO} cargo test ${CARGO_FLAGS} --package fish-rust --target-dir target ${cargo_target_opt}
         WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
     )
     set_tests_properties("cargo-test" PROPERTIES SKIP_RETURN_CODE ${SKIP_RETURN_CODE})
@@ -172,7 +172,7 @@ endif()
 
 add_test(
     NAME "cargo-test-widestring"
-    COMMAND cargo test ${CARGO_FLAGS} --package widestring-suffix --target-dir target ${cargo_target_opt}
+    COMMAND env ${VARS_FOR_CARGO} cargo test ${CARGO_FLAGS} --package widestring-suffix --target-dir target ${cargo_target_opt}
     WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
 )
 add_test_target("cargo-test-widestring")