diff --git a/Makefile b/Makefile
index 86f9ff28..9fd05266 100644
--- a/Makefile
+++ b/Makefile
@@ -112,7 +112,7 @@ ifeq ($(clean),yes)
 endif
 	$(eval target := $(strip $(shell cargo -vV | sed -n 's/host: //p')))
 	cargo build --all-features --tests
-	mdbook test book -L target/debug/deps $(strip \
+	OUT_DIR=target mdbook test book -L target/debug/deps $(strip \
 		$(if $(call eq,$(findstring windows,$(target)),),,\
 			$(shell cargo metadata -q \
 			        | jq -r '.packages[] | select(.name == "windows_$(word 1,$(subst -, ,$(target)))_$(word 4,$(subst -, ,$(target)))") | .manifest_path' \
diff --git a/book/README.md b/book/README.md
index 809ef9bb..80669c7f 100644
--- a/book/README.md
+++ b/book/README.md
@@ -48,7 +48,7 @@ To run the tests validating all code examples in the book, run (from project roo
 
 ```bash
 cargo build --all-features --tests
-mdbook test -L target/debug/deps
+OUT_DIR=target mdbook test -L target/debug/deps
 
 # or via shortcut:
 make test.book