diff --git a/src/script/nix-prefetch-bzr b/src/script/nix-prefetch-bzr
index 167892fb..574703d4 100755
--- a/src/script/nix-prefetch-bzr
+++ b/src/script/nix-prefetch-bzr
@@ -43,11 +43,10 @@ fi
 # If we don't know the hash or a path with that hash doesn't exist,
 # download the file and add it to the store.
 if test -z "$finalPath"; then
-    tmpPath=/tmp/bzr-checkout-tmp-$$
-    tmpFile=$tmpPath/$dstFile
-    mkdir $tmpPath
+    tmpPath="$(mktemp -d "${TMPDIR:-/tmp}/bzr-checkout-tmp-XXXXXXXX")"
+    trap "rm -rf \"$tmpPath\"" EXIT
 
-    trap "rm -rf $tmpPath" EXIT
+    tmpFile="$tmpPath/$dstFile"
 
     # Perform the checkout.
     if test "$NIX_PREFETCH_BZR_LEAVE_DOT_BZR" != 1
diff --git a/src/script/nix-prefetch-git b/src/script/nix-prefetch-git
index 979aa531..8aa599b9 100755
--- a/src/script/nix-prefetch-git
+++ b/src/script/nix-prefetch-git
@@ -237,11 +237,11 @@ else
   # download the file and add it to the store.
   if test -z "$finalPath"; then
 
-      tmpPath=/tmp/git-checkout-tmp-$$
-      tmpFile=$tmpPath/git-export
-      mkdir $tmpPath $tmpFile
+      tmpPath="$(mktemp -d "${TMPDIR:-/tmp}/git-checkout-tmp-XXXXXXXX")"
+      trap "rm -rf \"$tmpPath\"" EXIT
 
-      trap "rm -rf $tmpPath" EXIT
+      tmpFile="$tmpPath/git-export"
+      mkdir "$tmpFile"
 
       # Perform the checkout.
       clone_user_rev "$tmpFile" "$url" "$rev"
diff --git a/src/script/nix-prefetch-hg b/src/script/nix-prefetch-hg
index f1f648f4..4d78c68a 100755
--- a/src/script/nix-prefetch-hg
+++ b/src/script/nix-prefetch-hg
@@ -35,11 +35,10 @@ fi
 # download the file and add it to the store.
 if test -z "$finalPath"; then
 
-    tmpPath=/tmp/hg-checkout-tmp-$$
-    tmpArchive=$tmpPath/hg-archive
-    mkdir $tmpPath
+    tmpPath="$(mktemp -d "${TMPDIR:-/tmp}/hg-checkout-tmp-XXXXXXXX")"
+    trap "rm -rf \"$tmpPath\"" EXIT
 
-    trap "rm -rf $tmpPath" EXIT
+    tmpArchive="$tmpPath/hg-archive"
 
     # Perform the checkout.
     if [[ $url != /* ]]; then