diff --git a/components/ws-daemon/pkg/quota/size.go b/components/ws-daemon/pkg/quota/size.go
index d66895d9acd187..8216eda8035d5e 100644
--- a/components/ws-daemon/pkg/quota/size.go
+++ b/components/ws-daemon/pkg/quota/size.go
@@ -31,7 +31,7 @@ const (
 )
 
 var (
-	sizeRegexp = regexp.MustCompile(`(\d+)(k|m|g|t)?`)
+	sizeRegexp = regexp.MustCompile(`^(\d+)(k|m|g|t)?$`)
 
 	// ErrInvalidSize is returned by ParseSize if input was not a valid size
 	ErrInvalidSize = errors.New("invalid size")
diff --git a/components/ws-daemon/pkg/quota/size_test.go b/components/ws-daemon/pkg/quota/size_test.go
index cc21ae2579b1a2..3f1131ec1fa7da 100644
--- a/components/ws-daemon/pkg/quota/size_test.go
+++ b/components/ws-daemon/pkg/quota/size_test.go
@@ -23,8 +23,8 @@ func TestParseSize(t *testing.T) {
 		{"42m", 42 * quota.Megabyte, nil},
 		{"42g", 42 * quota.Gigabyte, nil},
 		{"42t", 42 * quota.Terabyte, nil},
-		// This test should fail but doesn't because match somehow matches the regexp
-		// {"-42m", 0, quota.ErrInvalidSize},
+		{"-42m", 0, quota.ErrInvalidSize},
+		{"ab-42mcd", 0, quota.ErrInvalidSize},
 		{"abc", 0, quota.ErrInvalidSize},
 		{"99999999999999999999999999999999999999999999999999999999999999999999999999999999", 0, quota.ErrInvalidSize},
 	}