diff --git a/.travis.yml b/.travis.yml
index d88f0670f7..33d28f5aa2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -46,7 +46,7 @@ matrix:
     - name: cargo +stable build --no-default-features
       rust: nightly
       env:
-        - RUSTFLAGS="-Z allow-features="
+        - RUSTFLAGS="-Z allow-features=proc_macro_span"
       script:
         - cargo run --manifest-path ci/remove-dev-dependencies/Cargo.toml */Cargo.toml
         - cargo build --manifest-path futures/Cargo.toml --no-default-features
@@ -60,7 +60,7 @@ matrix:
     - name: cargo +stable build (alloc)
       rust: nightly
       env:
-        - RUSTFLAGS="-Z allow-features="
+        - RUSTFLAGS="-Z allow-features=proc_macro_span"
       script:
         - cargo run --manifest-path ci/remove-dev-dependencies/Cargo.toml */Cargo.toml
         - cargo build --manifest-path futures/Cargo.toml --no-default-features --features alloc
@@ -71,7 +71,7 @@ matrix:
     - name: cargo +stable build (default features)
       rust: nightly
       env:
-        - RUSTFLAGS="-Z allow-features="
+        - RUSTFLAGS="-Z allow-features=proc_macro_span"
       script:
         - cargo run --manifest-path ci/remove-dev-dependencies/Cargo.toml */Cargo.toml
         - cargo build --all
@@ -79,7 +79,7 @@ matrix:
     - name: cargo +stable build (compat feature)
       rust: nightly
       env:
-        - RUSTFLAGS="-Z allow-features="
+        - RUSTFLAGS="-Z allow-features=proc_macro_span"
       script:
         - cargo run --manifest-path ci/remove-dev-dependencies/Cargo.toml */Cargo.toml
         - cargo build --manifest-path futures/Cargo.toml --features io-compat