diff --git a/doc/build-freebsd.md b/doc/build-freebsd.md
--- a/doc/build-freebsd.md
+++ b/doc/build-freebsd.md
@@ -26,7 +26,7 @@
 ```shell
 pkg install libzmq4
 ```
-If not installed, ZeroMQ support should be disabled by passing `-BUILD_BITCOIN_ZMQ=OFF` to `cmake`.
+If not installed, ZeroMQ support should be disabled by passing `-DBUILD_BITCOIN_ZMQ=OFF` to `cmake`.
 
 In order to run the test suite (recommended), you will need to have Python 3 installed:
 
diff --git a/doc/build-unix.md b/doc/build-unix.md
--- a/doc/build-unix.md
+++ b/doc/build-unix.md
@@ -104,7 +104,7 @@
 
     sudo apt-get install libminiupnpc-dev
 
-ZMQ dependencies (provides ZMQ API, can be disabled by passing `-BUILD_BITCOIN_ZMQ=OFF` on the cmake command line):
+ZMQ dependencies (provides ZMQ API, can be disabled by passing `-DBUILD_BITCOIN_ZMQ=OFF` on the cmake command line):
 
     sudo apt-get install libzmq3-dev
 
@@ -133,7 +133,7 @@
 
     sudo dnf install miniupnpc-devel
 
-ZMQ dependencies (can be disabled by passing `-BUILD_BITCOIN_ZMQ=OFF` on the cmake command line):
+ZMQ dependencies (can be disabled by passing `-DBUILD_BITCOIN_ZMQ=OFF` on the cmake command line):
 
     sudo dnf install zeromq-devel