diff --git a/CMakeLists.txt b/CMakeLists.txt
index ef7be72c87..abd40f0579 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -80,6 +80,8 @@ set(CPACK_SOURCE_IGNORE_FILES "" CACHE STRING "Files to be ignored by CPack")
 
 set(ZEEK_INCLUDE_PLUGINS "" CACHE STRING "Extra plugins to add to the build.")
 
+set(ZEEK_VERSION_LOCAL "" CACHE STRING "Custom version string.")
+
 # Look into the build tree for additional CMake modules.
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_BINARY_DIR})
 list(APPEND CMAKE_PREFIX_PATH ${CMAKE_BINARY_DIR})
diff --git a/docker/Makefile b/docker/Makefile
index 40a8d4ba93..306bc909e0 100644
--- a/docker/Makefile
+++ b/docker/Makefile
@@ -5,7 +5,7 @@ LOCALVERSION ?= ""
 LOCAL_VERSION_FLAG = ""
 ifneq ($(LOCALVERSION), "")
 	VERSION := $(VERSION)-$(LOCALVERSION)
-	LOCAL_VERSION_FLAG := "--localversion=$(LOCALVERSION)"
+	LOCAL_VERSION_FLAG := --localversion=$(LOCALVERSION)
 endif
 BUILD_IMAGE := zeek-builder:$(VERSION)
 BUILD_CONTAINER := zeek-builder-container-$(VERSION)