diff --git a/pkgs/build-support/bintools-wrapper/setup-hook.sh b/pkgs/build-support/bintools-wrapper/setup-hook.sh
index 43f79ec59200..c508963ac33e 100644
--- a/pkgs/build-support/bintools-wrapper/setup-hook.sh
+++ b/pkgs/build-support/bintools-wrapper/setup-hook.sh
@@ -2,12 +2,17 @@
 #
 # See comments in cc-wrapper's setup hook. This works exactly the same way.
 
+set -u
+
+# Skip setup hook if we're not a build-time dep
+(( "$hostOffset" < 0 )) || return 0
+
 bintoolsWrapper_addLDVars () {
-    case $depOffset in
+    case $depHostOffset in
         -1) local role='BUILD_' ;;
         0)  local role='' ;;
         1)  local role='TARGET_' ;;
-        *)  echo "bintools-wrapper: Error: Cannot be used with $depOffset-offset deps, " >2;
+        *)  echo "bintools-wrapper: Error: Cannot be used with $depHostOffset-offset deps" >2;
             return 1 ;;
     esac
 
@@ -20,17 +25,29 @@ bintoolsWrapper_addLDVars () {
     fi
 }
 
-if [ -n "${crossConfig:-}" ]; then
-    export NIX_BINTOOLS_WRAPPER_@infixSalt@_TARGET_BUILD=1
-    role_pre='BUILD_'
-    role_post='_FOR_BUILD'
-else
-    export NIX_BINTOOLS_WRAPPER_@infixSalt@_TARGET_HOST=1
-    role_pre=""
-    role_post=''
-fi
+case $targetOffset in
+    -1)
+        export NIX_BINTOOLS_WRAPPER_@infixSalt@_TARGET_BUILD=1
+        role_pre='BUILD_'
+        role_post='_FOR_BUILD'
+        ;;
+    0)
+        export NIX_BINTOOLS_WRAPPER_@infixSalt@_TARGET_HOST=1
+        role_pre=''
+        role_post=''
+        ;;
+    1)
+        export NIX_BINTOOLS_WRAPPER_@infixSalt@_TARGET_TARGET=1
+        role_pre='TARGET_'
+        role_post='_FOR_TARGET'
+        ;;
+    *)
+        echo "cc-wrapper: used as improper sort of dependency" >2;
+        return 1
+        ;;
+esac
 
-envHooks+=(bintoolsWrapper_addLDVars)
+addEnvHooks "$targetOffset" bintoolsWrapper_addLDVars
 
 # shellcheck disable=SC2157
 if [ -n "@bintools_bin@" ]; then
@@ -65,3 +82,4 @@ done
 
 # No local scope in sourced file
 unset -v role_pre role_post cmd upper_case
+set +u
diff --git a/pkgs/build-support/cc-wrapper/setup-hook.sh b/pkgs/build-support/cc-wrapper/setup-hook.sh
index a922193ad2e7..17877dc262c5 100644
--- a/pkgs/build-support/cc-wrapper/setup-hook.sh
+++ b/pkgs/build-support/cc-wrapper/setup-hook.sh
@@ -54,19 +54,23 @@
 # For more details, read the individual files where the mechanisms used to
 # accomplish this will be individually documented.
 
+set -u
+
+# Skip setup hook if we're not a build-time dep
+(( "$hostOffset" < 0 )) || return 0
 
 # It's fine that any other cc-wrapper will redefine this. Bash functions close
 # over no state, and there's no @-substitutions within, so any redefined
 # function is guaranteed to be exactly the same.
 ccWrapper_addCVars () {
-    # The `depOffset` describes how the platforms of the dependencies are slid
-    # relative to the depending package. It is brought into scope of the
-    # environment hook defined as the role of the dependency being applied.
-    case $depOffset in
+    # The `depHostOffset` describes how the host platform of the dependencies
+    # are slid relative to the depending package. It is brought into scope of
+    # the environment hook defined as the role of the dependency being applied.
+    case $depHostOffset in
         -1) local role='BUILD_' ;;
         0)  local role='' ;;
         1)  local role='TARGET_' ;;
-        *)  echo "cc-wrapper: Error: Cannot be used with $depOffset-offset deps, " >2;
+        *)  echo "cc-wrapper: Error: Cannot be used with $depHostOffset-offset deps" >2;
             return 1 ;;
     esac
 
@@ -87,20 +91,31 @@ ccWrapper_addCVars () {
 #
 # We also need to worry about what role is being added on *this* invocation of
 # setup-hook, which `role` tracks.
-if [ -n "${crossConfig:-}" ]; then
-    export NIX_CC_WRAPPER_@infixSalt@_TARGET_BUILD=1
-    role_pre='BUILD_'
-    role_post='_FOR_BUILD'
-else
-    export NIX_CC_WRAPPER_@infixSalt@_TARGET_HOST=1
-    role_pre=''
-    role_post=''
-fi
+case $targetOffset in
+    -1)
+        export NIX_CC_WRAPPER_@infixSalt@_TARGET_BUILD=1
+        role_pre='BUILD_'
+        role_post='_FOR_BUILD'
+        ;;
+    0)
+        export NIX_CC_WRAPPER_@infixSalt@_TARGET_HOST=1
+        role_pre=''
+        role_post=''
+        ;;
+    1)
+        export NIX_CC_WRAPPER_@infixSalt@_TARGET_TARGET=1
+        role_pre='TARGET_'
+        role_post='_FOR_TARGET'
+        ;;
+    *)
+        echo "cc-wrapper: used as improper sort of dependency" >2;
+        return 1
+        ;;
+esac
 
-# Eventually the exact sort of env-hook we create will depend on the role. This
-# is because based on what relative platform we are targeting, we use different
-# dependencies.
-envHooks+=(ccWrapper_addCVars)
+# We use the `targetOffset` to choose the right env hook to accumulate the right
+# sort of deps (those with that offset).
+addEnvHooks "$targetOffset" ccWrapper_addCVars
 
 # Note 1: these come *after* $out in the PATH (see setup.sh).
 # Note 2: phase separation makes this look useless to shellcheck.
@@ -131,3 +146,4 @@ export CXX${role_post}=@named_cxx@
 
 # No local scope in sourced file
 unset -v role_pre role_post
+set +u
diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index b2b15c74d4e8..1850d322cc69 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -326,6 +326,17 @@ declare -ra pkgTargetHookVars=(envTargetTargetHook)
 
 declare -ra pkgHookVarVars=(pkgBuildHookVars pkgHostHookVars pkgTargetHookVars)
 
+# Add env hooks for all sorts of deps with the specified host offset.
+addEnvHooks() {
+    local depHostOffset="$1"
+    shift
+    local pkgHookVarsSlice="${pkgHookVarVars[$depHostOffset + 1]}[@]"
+    local pkgHookVar
+    for pkgHookVar in "${!pkgHookVarsSlice}"; do
+        eval "${pkgHookVar}s"'+=("$@")'
+    done
+}
+
 
 # Propagated dep files