diff --git a/CHANGES b/CHANGES
index d1ba82353c..927587da24 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,15 @@
+6.0.0-dev.643 | 2023-05-25 09:03:40 -0700
+
+  * btest.cfg: Set HILTI_CXX_COMPILER_LAUNCHER based on build/CMakeCache.txt (Arne Welzel, Corelight)
+
+    If CMakeCache.txt indicates the Zeek build was done with ccache,
+    take the CCACHE_PROGRAM:FILEPATH= line and populate the
+    HILTI_CXX_COMPILER_LAUNCHER environment.
+
+    For local development with ccache, this speeds up the spicy tests
+    significantly after the initial run without knowing or needing know
+    that setting HILTI_CXX_COMPILER_LAUNCHER would've helped.
+
 6.0.0-dev.641 | 2023-05-25 09:03:08 -0700
 
   * Speed up Spicy-related tests. (Benjamin Bannier, Corelight)
diff --git a/VERSION b/VERSION
index cbd66c7517..55da7b02ff 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.0.0-dev.641
+6.0.0-dev.643
diff --git a/testing/btest/btest.cfg b/testing/btest/btest.cfg
index 8ece31ab15..535e51befb 100644
--- a/testing/btest/btest.cfg
+++ b/testing/btest/btest.cfg
@@ -13,6 +13,7 @@ MinVersion  = 0.63
 
 [environment]
 ZEEKPATH=`bash -c %(testbase)s/../../%(build_dir)s/zeek-path-dev`
+HILTI_CXX_COMPILER_LAUNCHER=`f=%(testbase)s/../../%(build_dir)s/CMakeCache.txt && grep -q '^ENABLE_CCACHE:BOOL=true' $f && sed -n 's/^CCACHE_PROGRAM:FILEPATH=\(.*\)$/\1/p' $f`
 ZEEK_SEED_FILE=%(testbase)s/random.seed
 ZEEK_PLUGIN_PATH=
 TZ=UTC