diff --git a/R/aaa.R b/R/aaa.R
index 568a2aa..bfdab4c 100644
--- a/R/aaa.R
+++ b/R/aaa.R
@@ -5,4 +5,21 @@ TBB_LIB  <- ""
 TBB_INC  <- ""
 
 TBB_NAME <- "tbb"
-TBB_MALLOC_NAME <- "tbbmalloc"
\ No newline at end of file
+TBB_MALLOC_NAME <- "tbbmalloc"
+
+# bincraft patch: our build images (and plenty of user environments) export
+# TBB_ROOT / TBB_LIB / TBB_INC. A binary we publish always carries its own
+# oneTBB in RcppParallel/lib -- see the companion changes in
+# tools/config/configure.R and src/install.libs.R -- so honouring those
+# variables at run time is actively harmful: .onLoad() would dyn.load() a
+# second, unrelated TBB into the process next to the bundled one (two copies
+# of the same symbols in the global scope, which segfaults R on load), and
+# RcppParallelLibs() / CxxFlags() would hand that system TBB to dependents
+# such as rstan, putting NEEDED libtbb.so.12 back into their binaries. Read
+# the variables only when explicitly opted back in.
+bincraftGetenv <- function(name, unset = "") {
+   if (Sys.getenv("BINCRAFT_ALLOW_SYSTEM_TBB", unset = "FALSE") == "TRUE")
+      Sys.getenv(name, unset = unset)
+   else
+      unset
+}
\ No newline at end of file
diff --git a/R/tbb.R b/R/tbb.R
index 6f6a745..e407986 100644
--- a/R/tbb.R
+++ b/R/tbb.R
@@ -17,7 +17,7 @@ tbbLibraryPath <- function(name = NULL) {
    sysname <- Sys.info()[["sysname"]]
 
    # find root for TBB install
-   tbbRoot <- Sys.getenv("TBB_LIB", unset = tbbRoot())
+   tbbRoot <- bincraftGetenv("TBB_LIB", unset = tbbRoot())
    if (is.null(name))
       return(tbbRoot)
 
@@ -58,3 +58,3 @@ tbbCxxFlags <- function() {
    # if TBB_INC is set, apply those library paths
-   tbbInc <- Sys.getenv("TBB_INC", unset = TBB_INC)
+   tbbInc <- bincraftGetenv("TBB_INC", unset = TBB_INC)
    if (!file.exists(tbbInc)) {
@@ -117,7 +117,7 @@ tbbLdFlags <- function() {
    }
 
    # shortcut if TBB_LIB defined
-   tbbLib <- Sys.getenv("TBB_LINK_LIB", Sys.getenv("TBB_LIB", unset = TBB_LIB))
+   tbbLib <- bincraftGetenv("TBB_LINK_LIB", bincraftGetenv("TBB_LIB", unset = TBB_LIB))
    if (nzchar(tbbLib)) {
       if (R.version$os == "emscripten") {
          fmt <- "-L%1$s -l%2$s"
diff --git a/src/install.libs.R b/src/install.libs.R
index 3b3cfda..c0e6f3e 100644
--- a/src/install.libs.R
+++ b/src/install.libs.R
@@ -477,6 +477,18 @@ prependFlags <- function(prependFlags, toFlags) {
 tbbLib <- Sys.getenv("TBB_LIB")
 tbbInc <- Sys.getenv("TBB_INC")
 
+# bincraft patch: the companion change in tools/config/configure.R stops an
+# ambient TBB_LIB / TBB_INC from selecting a system TBB, but this script is
+# also run directly by `R CMD INSTALL` (not only through the `tbb` rule in
+# src/Makevars, which passes the configured values), so at install time it
+# still sees the image's environment and would symlink the system libraries
+# into RcppParallel/lib. Drop them here for the same reason, under the same
+# opt-out.
+if (Sys.getenv("BINCRAFT_ALLOW_SYSTEM_TBB", unset = "FALSE") != "TRUE") {
+   tbbLib <- ""
+   tbbInc <- ""
+}
+
 args <- commandArgs(trailingOnly = TRUE)
 if (identical(args, "build")) {
    if (nzchar(tbbLib) && nzchar(tbbInc)) {
diff --git a/tools/config/configure.R b/tools/config/configure.R
index 6293fe1..eae4aaa 100644
--- a/tools/config/configure.R
+++ b/tools/config/configure.R
@@ -40,6 +40,24 @@ tbbRoot  <- Sys.getenv("TBB_ROOT", unset = NA)
 tbbLib   <- Sys.getenv("TBB_LIB", unset = NA)
 tbbInc   <- Sys.getenv("TBB_INC", unset = NA)
 
+# bincraft patch: ignore an ambient TBB_ROOT / TBB_LIB / TBB_INC. Several of
+# our build images export these (a leftover from RcppParallel 5.x, whose
+# bundled Intel TBB would not build on musl or with modern g++), and any of
+# them switches the branches below to a system TBB. The published binary then
+# records NEEDED libtbb.so.12 (or libtbb.so.2 for the classic Intel TBB) and
+# gets a RcppParallel/lib full of absolute symlinks into the image's library
+# dir, so it cannot dyn.load on a consumer machine without that exact TBB.
+# 6.x bundles oneTBB 2022 and builds it with cmake on every platform we ship,
+# so the bundled copy is always the right choice here; forcing it in the
+# package rather than relying on the image environment keeps the binary
+# correct whichever image version CI happens to pull. Set
+# BINCRAFT_ALLOW_SYSTEM_TBB=TRUE to restore the upstream behaviour.
+if (Sys.getenv("BINCRAFT_ALLOW_SYSTEM_TBB", unset = "FALSE") != "TRUE") {
+   tbbRoot <- NA
+   tbbLib  <- NA
+   tbbInc  <- NA
+}
+
 tbbName  <- Sys.getenv("TBB_NAME", unset = "tbb")
 tbbMallocName <- Sys.getenv("TBB_MALLOC_NAME", unset = "tbbmalloc")
 
@@ -186,12 +204,23 @@ define(
 )
 
 # set PKG_LIBS
+#
+# bincraft patch: the library directories below are passed as plain '-L', not
+# '-Wl,-L'. gcc expands its own search dirs (/usr/lib64, /usr/lib/<triplet>)
+# into explicit '-L' options ahead of anything forwarded verbatim with '-Wl,',
+# so with '-Wl,-L' a system libtbb.so wins over the one named here: on a build
+# host with a distro TBB installed, '-ltbb' resolves to that library and
+# RcppParallel.so records its SONAME (libtbb.so.12, or libtbb.so.2 for the
+# classic Intel TBB) instead of the bundled 'libtbb.so'. The binary then loads
+# the system TBB rather than the copy shipped in RcppParallel/lib, and fails
+# outright on a machine that has no system TBB. gcc places a plain '-L' before
+# its built-in dirs, so the intended library is found first.
 pkgLibs <- if (!is.na(tbbLib)) {
 
    # a TBB supplied via TBB_LIB / TBB_ROOT. an rpath is meaningless on Windows,
    # where the loader has no equivalent -- see R/zzz.R for how we resolve there
    c(
-      "-Wl,-L\"$(TBB_LIB)\"",
+      "-L\"$(TBB_LIB)\"",
       if (.Platform$OS.type != "windows")
          sprintf("-Wl,-rpath,%s", shQuote(tbbLib)),
       "-l$(TBB_NAME)",
@@ -201,14 +230,14 @@ pkgLibs <- if (!is.na(tbbLib)) {
 } else if (R.version$os == "emscripten") {
 
    c(
-      "-Wl,-Ltbb/build/lib_release",
+      "-Ltbb/build/lib_release",
       "-l$(TBB_NAME)"
    )
 
 } else {
 
    c(
-      "-Wl,-Ltbb/build/lib_release",
+      "-Ltbb/build/lib_release",
       "-l$(TBB_NAME)",
       "-l$(TBB_MALLOC_NAME)"
    )