diff --git a/eclass/llvm-utils.eclass b/eclass/llvm-utils.eclass
index abe8bb7d7d0fd..98fc814084152 100644
--- a/eclass/llvm-utils.eclass
+++ b/eclass/llvm-utils.eclass
@@ -126,10 +126,9 @@ llvm_fix_tool_path() {
 llvm_prepend_path() {
 	debug-print-function ${FUNCNAME} "$@"
 
-	local prefix
-	case ${1--d} in
+	local prefix=${ESYSROOT}
+	case ${1} in
 		-d)
-			prefix=${ESYSROOT}
 			shift
 			;;
 		-b)
diff --git a/eclass/tests/llvm-utils.sh b/eclass/tests/llvm-utils.sh
index 4ba767a442f2d..a3219d23b491f 100755
--- a/eclass/tests/llvm-utils.sh
+++ b/eclass/tests/llvm-utils.sh
@@ -104,6 +104,8 @@ test_fix_tool_path AR ar 1
 test_fix_tool_path AR ar 0
 
 ESYSROOT=
+einfo "Testing with ESYSROOT=${ESYSROOT}"
+eindent
 test_prepend_path 17 /usr/bin /usr/bin:/usr/lib/llvm/17/bin
 test_prepend_path 17 /usr/lib/llvm/17/bin:/usr/bin /usr/lib/llvm/17/bin:/usr/bin
 test_prepend_path 17 /usr/bin:/usr/lib/llvm/17/bin /usr/bin:/usr/lib/llvm/17/bin
@@ -123,5 +125,24 @@ test_prepend_path 18 /usr/bin:/usr/lib/llvm/17/bin:/usr/lib/llvm/16/bin \
 	/usr/bin:/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin:/usr/lib/llvm/16/bin
 test_prepend_path 18 /usr/lib/llvm/17/bin:/usr/bin:/usr/lib/llvm/16/bin \
 	/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin:/usr/bin:/usr/lib/llvm/16/bin
+eoutdent
+
+ESYSROOT=/foo
+einfo "Testing with ESYSROOT=${ESYSROOT}"
+eindent
+test_prepend_path 17 /usr/bin /usr/bin:/foo/usr/lib/llvm/17/bin
+test_prepend_path 17 /usr/lib/llvm/17/bin:/usr/bin \
+	/foo/usr/lib/llvm/17/bin:/usr/lib/llvm/17/bin:/usr/bin
+test_prepend_path 17 /usr/bin:/usr/lib/llvm/17/bin: \
+	/usr/bin:/foo/usr/lib/llvm/17/bin:/usr/lib/llvm/17/bin
+test_prepend_path 17 /foo/usr/lib/llvm/17/bin:/usr/bin \
+	/foo/usr/lib/llvm/17/bin:/usr/bin
+test_prepend_path 17 /usr/bin:/foo/usr/lib/llvm/17/bin: \
+	/usr/bin:/foo/usr/lib/llvm/17/bin
+test_prepend_path 18 /usr/lib/llvm/17/bin:/usr/bin \
+	/foo/usr/lib/llvm/18/bin:/usr/lib/llvm/17/bin:/usr/bin
+test_prepend_path 18 /foo/usr/lib/llvm/17/bin:/usr/bin \
+	/foo/usr/lib/llvm/18/bin:/foo/usr/lib/llvm/17/bin:/usr/bin
+eoutdent
 
 texit