diff --git a/CMakeLists.txt b/CMakeLists.txt
index 15f32f846..d161def83 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,6 +28,24 @@ set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
 # This defines the FBVF variable.
 include(Version)
 
+# Set up the docs.
+include(cmake/Docs.cmake)
+
+# Tell Cargo where our build directory is so it can find Cargo.toml.
+set(VARS_FOR_CARGO
+    "FISH_CMAKE_BINARY_DIR=${CMAKE_BINARY_DIR}"
+    "PREFIX=${CMAKE_INSTALL_PREFIX}"
+    "DOCDIR=${CMAKE_INSTALL_FULL_DOCDIR}"
+    "DATADIR=${CMAKE_INSTALL_FULL_DATADIR}"
+    "SYSCONFDIR=${CMAKE_INSTALL_FULL_SYSCONFDIR}"
+    "BINDIR=${CMAKE_INSTALL_FULL_BINDIR}"
+    "CARGO_TARGET_DIR=${FISH_RUST_BUILD_DIR}"
+    "CARGO_BUILD_RUSTC=${Rust_COMPILER}"
+    "${FISH_PCRE2_BUILDFLAG}"
+    "RUSTFLAGS=$ENV{RUSTFLAGS} ${rust_debugflags}"
+    "FISH_SPHINX=${SPHINX_EXECUTABLE}"
+)
+
 # Let fish pick up when we're running out of the build directory without installing
 get_filename_component(REAL_CMAKE_BINARY_DIR "${CMAKE_BINARY_DIR}" REALPATH)
 get_filename_component(REAL_CMAKE_SOURCE_DIR "${CMAKE_SOURCE_DIR}" REALPATH)
@@ -71,9 +89,6 @@ create_target(fish_indent)
 # Define fish_key_reader.
 create_target(fish_key_reader)
 
-# Set up the docs.
-include(cmake/Docs.cmake)
-
 # Set up tests.
 include(cmake/Tests.cmake)
 
diff --git a/cmake/Rust.cmake b/cmake/Rust.cmake
index b19451399..1de0da580 100644
--- a/cmake/Rust.cmake
+++ b/cmake/Rust.cmake
@@ -30,17 +30,3 @@ if(NOT DEFINED WITH_GETTEXT OR "${WITH_GETTEXT}")
 endif()
 
 list(JOIN FISH_CARGO_FEATURES_LIST , FISH_CARGO_FEATURES)
-
-# Tell Cargo where our build directory is so it can find Cargo.toml.
-set(VARS_FOR_CARGO
-    "FISH_CMAKE_BINARY_DIR=${CMAKE_BINARY_DIR}"
-    "PREFIX=${CMAKE_INSTALL_PREFIX}"
-    "DOCDIR=${CMAKE_INSTALL_FULL_DOCDIR}"
-    "DATADIR=${CMAKE_INSTALL_FULL_DATADIR}"
-    "SYSCONFDIR=${CMAKE_INSTALL_FULL_SYSCONFDIR}"
-    "BINDIR=${CMAKE_INSTALL_FULL_BINDIR}"
-    "CARGO_TARGET_DIR=${FISH_RUST_BUILD_DIR}"
-    "CARGO_BUILD_RUSTC=${Rust_COMPILER}"
-    "${FISH_PCRE2_BUILDFLAG}"
-    "RUSTFLAGS=$ENV{RUSTFLAGS} ${rust_debugflags}"
-)
diff --git a/crates/build-man-pages/build.rs b/crates/build-man-pages/build.rs
index 011c73355..b444c2067 100644
--- a/crates/build-man-pages/build.rs
+++ b/crates/build-man-pages/build.rs
@@ -54,7 +54,7 @@ fn build_man(man_dir: &Path) {
     // - if we skipped the docs with sphinx not installed, installing it would not then build the docs.
     // That means you need to explicitly set $FISH_BUILD_DOCS=0 (`FISH_BUILD_DOCS=0 cargo install --path .`),
     // which is unfortunate - but the docs are pretty important because they're also used for --help.
-    let sphinx_build = match Command::new("sphinx-build")
+    let sphinx_build = match Command::new(option_env!("FISH_SPHINX").unwrap_or("sphinx-build"))
         .args(args)
         .stdout(Stdio::piped())
         .stderr(Stdio::piped())