diff --git a/src/Makevars b/src/Makevars
index 88ca9c9..c251885 100644
--- a/src/Makevars
+++ b/src/Makevars
@@ -23,7 +23,7 @@ $(STATLIB):
  			export CARGO_HOME=$(CARGOTMP); \
 		fi && \
 		echo "*** Rust version: $$(rustc --version)" && \
-		cargo build --lib --release --offline --config rust/config/cargo-config.toml --manifest-path=./rust/Cargo.toml --target-dir $(TARGET_DIR)
+		cargo build --lib --release --offline --config rust/config/cargo-config.toml --manifest-path=./rust/Cargo.toml --target-dir $(TARGET_DIR) --jobs 1
 
 	# we clean headers to avoid a message like
 	# Found the following sources/headers with CR or CRLF line endings:
diff --git a/src/Makevars.win b/src/Makevars.win
index eea85cd..e9d1dfe 100644
--- a/src/Makevars.win
+++ b/src/Makevars.win
@@ -32,7 +32,7 @@ $(STATLIB):
  			export CARGO_HOME=$(CARGOTMP); \
 		fi && \
 		echo "*** Rust version: $$(rustc --version)" && \
-		cargo build --target=$(TARGET) --lib --release --offline --config rust/config/cargo-config.toml --manifest-path=./rust/Cargo.toml --target-dir $(TARGET_DIR)
+		cargo build --target=$(TARGET) --lib --release --offline --config rust/config/cargo-config.toml --manifest-path=./rust/Cargo.toml --target-dir $(TARGET_DIR) --jobs 1
 	
 	# we clean headers to avoid a message like
 	# Found the following sources/headers with CR or CRLF line endings: