diff --git a/nix/libstore/gc.cc b/nix/libstore/gc.cc
index 4babea4a50..05d332f2a1 100644
--- a/nix/libstore/gc.cc
+++ b/nix/libstore/gc.cc
@@ -301,12 +301,8 @@ static void findRoots(StoreAPI & store, const Path & path, unsigned char type, R
 {
     try {
 
-        if (type == DT_UNKNOWN) {
-            struct stat st = lstat(path);
-            if (S_ISDIR(st.st_mode)) type = DT_DIR;
-            else if (S_ISLNK(st.st_mode)) type = DT_LNK;
-            else if (S_ISREG(st.st_mode)) type = DT_REG;
-        }
+        if (type == DT_UNKNOWN)
+            type = getFileType(path);
 
         if (type == DT_DIR) {
             for (auto & i : readDirectory(path))
diff --git a/nix/libutil/util.cc b/nix/libutil/util.cc
index 9af42a150c..ad3b3c387f 100644
--- a/nix/libutil/util.cc
+++ b/nix/libutil/util.cc
@@ -223,6 +223,16 @@ DirEntries readDirectory(const Path & path)
 }
 
 
+unsigned char getFileType(const Path & path)
+{
+    struct stat st = lstat(path);
+    if (S_ISDIR(st.st_mode)) return DT_DIR;
+    if (S_ISLNK(st.st_mode)) return DT_LNK;
+    if (S_ISREG(st.st_mode)) return DT_REG;
+    return DT_UNKNOWN;
+}
+
+
 string readFile(int fd)
 {
     struct stat st;
diff --git a/nix/libutil/util.hh b/nix/libutil/util.hh
index 7e538ea033..418d76daec 100644
--- a/nix/libutil/util.hh
+++ b/nix/libutil/util.hh
@@ -77,6 +77,8 @@ typedef vector<DirEntry> DirEntries;
 
 DirEntries readDirectory(const Path & path);
 
+unsigned char getFileType(const Path & path);
+
 /* Read the contents of a file into a string. */
 string readFile(int fd);
 string readFile(const Path & path, bool drain = false);