diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1edd18b5f..0d35e1f66 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -505,7 +505,7 @@ install(TARGETS notcurses
     COMPONENT Development
 )
 if(${BUILD_PYTHON})
-  if(DEFINED $ENV{DEB_BUILD_ARCH})
+  if(DEFINED ENV{DEB_BUILD_ARCH})
     install(
       CODE
       "execute_process(COMMAND ${Python3_EXECUTABLE} ${SETUP_PY} install --root=${CMAKE_SOURCE_DIR}/debian/python3-notcurses --install-layout=deb --prefix=${CMAKE_INSTALL_PREFIX} WORKING_DIRECTORY ../python)")