diff --git a/CMakeFiles/MuParser.cmake b/CMakeFiles/MuParser.cmake
deleted file mode 100644
index 525181f6f..000000000
--- a/CMakeFiles/MuParser.cmake
+++ /dev/null
@@ -1,28 +0,0 @@
-INCLUDE(ExternalProject)
-
-SET(MUPARSER_PREFIX muparser-build)
-SET(MUPARSER_SRC ${CMAKE_CURRENT_SOURCE_DIR}/muparser-2.2.5)
-SET(MUPARSER_OBJ ${MUPARSER_PREFIX}/obj)
-SET(MUPARSER_DST ${MUPARSER_PREFIX}/dst)
-
-# MuParser configure has an obnoxious victory message which we suppress.
-EXTERNALPROJECT_ADD(
-  muparser_project
-  PREFIX ${MUPARSER_PREFIX}
-  SOURCE_DIR ${MUPARSER_SRC}
-  BINARY_DIR ${MUPARSER_OBJ}
-  INSTALL_DIR ${MUPARSER_DST}
-  CONFIGURE_COMMAND ${MUPARSER_SRC}/configure
-                    --prefix=${CMAKE_CURRENT_BINARY_DIR}/${MUPARSER_DST}
-                    --quiet --enable-shared=no --enable-samples=no --enable-debug=no > /dev/null
-  BUILD_COMMAND make -j 3 CPPFLAGS=-D_UNICODE=1\ -Wno-switch lib/libmuparser.a
-  INSTALL_COMMAND make install
-  BUILD_BYPRODUCTS ${MUPARSER_DST}/lib/libmuparser.a
-  EXCLUDE_FROM_ALL
-)
-
-ADD_LIBRARY(muparser STATIC IMPORTED)
-SET_TARGET_PROPERTIES(muparser PROPERTIES IMPORTED_LOCATION
-                      ${CMAKE_CURRENT_BINARY_DIR}/${MUPARSER_DST}/lib/libmuparser.a)
-ADD_DEPENDENCIES(muparser muparser_project)
-INCLUDE_DIRECTORIES(${CMAKE_CURRENT_BINARY_DIR}/${MUPARSER_DST}/include/)
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9501887bb..2165445c0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -76,7 +76,7 @@ ADD_DEFINITIONS(-D_UNICODE=1
 INCLUDE(CMakeFiles/PCRE2.cmake)
 
 # Set up muparser.
-INCLUDE(CMakeFiles/MuParser.cmake)
+INCLUDE(muparser-2.2.5/CMakeLists.txt)
 
 # Set up the docs.
 INCLUDE(CMakeFiles/Docs.cmake)
@@ -93,9 +93,6 @@ TARGET_LINK_LIBRARIES(fishlib
   ${CURSES_LIBRARY} ${CURSES_EXTRA_LIBRARY} Threads::Threads ${CMAKE_DL_LIBS}
   ${PCRE2_LIB} muparser)
 
-# builtin_math.cpp needs to see muParser's built header.
-ADD_DEPENDENCIES(fishlib muparser)
-
 # Define fish.
 ADD_EXECUTABLE(fish src/fish.cpp)
 FISH_LINK_DEPS(fish)
diff --git a/muparser-2.2.5/CMakeLists.txt b/muparser-2.2.5/CMakeLists.txt
new file mode 100644
index 000000000..ffb092541
--- /dev/null
+++ b/muparser-2.2.5/CMakeLists.txt
@@ -0,0 +1,12 @@
+SET(MUPARSER_SRCS
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParser.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParserBase.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParserBytecode.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParserCallback.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParserDLL.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParserError.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParserInt.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/src/muParserTokenReader.cpp)
+
+ADD_LIBRARY(muparser STATIC ${MUPARSER_SRCS})
+TARGET_INCLUDE_DIRECTORIES(muparser PUBLIC ${CMAKE_CURRENT_LIST_DIR}/include)