diff --git a/meta/classes/cmake.bbclass b/meta/classes/cmake.bbclass
index 20d8a61069..12df617ad8 100644
--- a/meta/classes/cmake.bbclass
+++ b/meta/classes/cmake.bbclass
@@ -1,5 +1,5 @@
 # Path to the CMake file to process.
-OECMAKE_SOURCEPATH ?= "${S}"
+OECMAKE_SOURCEPATH ??= "${S}"
 
 DEPENDS_prepend = "cmake-native "
 B = "${WORKDIR}/build"