diff --git a/.gitmodules b/.gitmodules
index 38e0606337..2ae43fe865 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -76,3 +76,6 @@
 [submodule "auxil/prometheus-cpp"]
 	path = auxil/prometheus-cpp
 	url = https://github.com/zeek/prometheus-cpp
+[submodule "auxil/expected-lite"]
+	path = auxil/expected-lite
+	url = https://github.com/martinmoene/expected-lite.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5f4c0a3d6b..f7969404db 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -358,6 +358,7 @@ add_zeek_dynamic_plugin_build_interface_include_directories(
     ${PROJECT_SOURCE_DIR}/auxil/paraglob/include
     ${PROJECT_SOURCE_DIR}/auxil/rapidjson/include
     ${PROJECT_SOURCE_DIR}/auxil/prometheus-cpp/core/include
+    ${PROJECT_SOURCE_DIR}/auxil/expected-lite/include
     ${CMAKE_BINARY_DIR}/src
     ${CMAKE_BINARY_DIR}/src/include
     ${CMAKE_BINARY_DIR}/auxil/binpac/lib
@@ -372,6 +373,10 @@ target_include_directories(
     zeek_dynamic_plugin_base SYSTEM
     INTERFACE $<INSTALL_INTERFACE:include/zeek/3rdparty/prometheus-cpp/include>)
 
+target_include_directories(
+    zeek_dynamic_plugin_base SYSTEM
+    INTERFACE $<INSTALL_INTERFACE:include/zeek/3rdparty/expected-lite/include>)
+
 # Convenience function for adding an OBJECT library that feeds directly into the
 # main target(s).
 #
@@ -1035,6 +1040,9 @@ install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/auxil/prometheus-cpp/core/include/
 install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/auxil/prometheus-cpp/core/include/prometheus
         DESTINATION include/zeek/3rdparty/prometheus-cpp/include)
 
+install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/auxil/expected-lite/include/nonstd
+        DESTINATION include/zeek/3rdparty/)
+
 # Create 3rdparty/ghc within the build directory so that the include for
 # "zeek/3rdparty/ghc/filesystem.hpp" works within the build tree.
 execute_process(COMMAND "${CMAKE_COMMAND}" -E make_directory
@@ -1045,6 +1053,13 @@ execute_process(
         "${CMAKE_CURRENT_SOURCE_DIR}/auxil/filesystem/include/ghc"
         "${CMAKE_CURRENT_BINARY_DIR}/3rdparty/ghc")
 
+# Do the same for nonstd.
+execute_process(
+    COMMAND
+        "${CMAKE_COMMAND}" -E create_symlink
+        "${CMAKE_CURRENT_SOURCE_DIR}/auxil/expected-lite/include/nonstd"
+        "${CMAKE_CURRENT_BINARY_DIR}/3rdparty/nonstd")
+
 # Optional Dependencies
 
 set(USE_GEOIP false)
diff --git a/auxil/expected-lite b/auxil/expected-lite
new file mode 160000
index 0000000000..f339d2f737
--- /dev/null
+++ b/auxil/expected-lite
@@ -0,0 +1 @@
+Subproject commit f339d2f73730f8fee4412f5e4938717866ecef48