diff --git a/third-party/cmake/FindFLEX.cmake b/third-party/cmake/FindFLEX.cmake
index cd54832c3..bc931d46a 100644
--- a/third-party/cmake/FindFLEX.cmake
+++ b/third-party/cmake/FindFLEX.cmake
@@ -113,7 +113,7 @@ IF(FLEX_EXECUTABLE)
       MESSAGE("Command \"${FLEX_EXECUTABLE} --version\" failed with output:\n${FLEX_version_output}\n${FLEX_version_error}\nFLEX_VERSION will not be available")
     ENDIF()
   ELSE()
-    STRING(REGEX REPLACE "^flex (.*)$" "\\1"
+    STRING(REGEX REPLACE "^flex[^ ]* (.*)$" "\\1"
       FLEX_VERSION "${FLEX_version_output}")
   ENDIF()