diff --git a/build/build-jasp.sh b/build/build-jasp.sh
index a6c2079..12c9c9b 100755
--- a/build/build-jasp.sh
+++ b/build/build-jasp.sh
@@ -268,6 +268,30 @@ PY
 # with less parallelism than the C++ build uses.
 R_JOBS="${R_JOBS:-2}"
 export MAKEFLAGS="-j${R_JOBS}"
+# R leaves 00LOCK-<pkg> directories behind when an install is interrupted, and
+# refuses to touch the library afterwards ("failed to lock directory ... for
+# modifying"). A build that is killed mid-install - a timeout, an OOM, a stopped
+# container - therefore poisons the library for every later run.
+log "clearing stale R install locks"
+rm -rf "${MODULE_LIBRARY}"/00LOCK-* 2>/dev/null || true
+
+# The interrupted install can also leave the library without devtools, which
+# buildModuleBundlesLocally.R calls unconditionally. Reinstall whatever is
+# missing rather than assuming a clean slate.
+Rscript -e "
+  lib <- '${MODULE_LIBRARY}'
+  dir.create(lib, recursive = TRUE, showWarnings = FALSE)
+  .libPaths(new = lib)
+  for (pkg in c('remotes', 'devtools')) {
+    if (!requireNamespace(pkg, lib.loc = lib, quietly = TRUE)) {
+      message('installing missing ', pkg)
+      install.packages(pkg, lib = lib, repos = 'https://cran.r-project.org')
+    }
+    if (!requireNamespace(pkg, lib.loc = lib, quietly = TRUE))
+      stop('failed to install ', pkg)
+  }
+"
+
 log "compiling R packages with -j${R_JOBS} (OpenMx needs the headroom)"
 
 # Build only the modules JASP actually ships. Modules/modules-settings.json