diff --git a/cmake/PCRE2.cmake b/cmake/PCRE2.cmake
index 372cadd58..5752eedea 100644
--- a/cmake/PCRE2.cmake
+++ b/cmake/PCRE2.cmake
@@ -3,8 +3,7 @@ set(FISH_USE_SYSTEM_PCRE2 ON CACHE BOOL
 
 if(FISH_USE_SYSTEM_PCRE2)
   message(STATUS "Trying to use PCRE2 from the system")
-  set(FISH_PCRE2_BUILDFLAG "")
 else()
   message(STATUS "Forcing static build of PCRE2")
-  set(ENV{PCRE2_SYS_STATIC} "1")
+  set(FISH_PCRE2_BUILDFLAG "PCRE2_SYS_STATIC=1")
 endif(FISH_USE_SYSTEM_PCRE2)
diff --git a/cmake/Rust.cmake b/cmake/Rust.cmake
index ba66a0078..7a7949663 100644
--- a/cmake/Rust.cmake
+++ b/cmake/Rust.cmake
@@ -56,5 +56,6 @@ set(VARS_FOR_CARGO
     "LOCALEDIR=${CMAKE_INSTALL_FULL_LOCALEDIR}"
     "CARGO_TARGET_DIR=${FISH_RUST_BUILD_DIR}"
     "CARGO_BUILD_RUSTC=${RUSTC_EXECUTABLE}"
+    "${FISH_PCRE2_BUILDFLAG}"
     "RUSTFLAGS=$ENV{RUSTFLAGS} ${rust_debugflags}"
 )