diff --git a/libguile/hash.c b/libguile/hash.c
index ab47008f0..d47c7e054 100644
--- a/libguile/hash.c
+++ b/libguile/hash.c
@@ -286,8 +286,9 @@ scm_raw_ihash (SCM obj, size_t depth)
 	size_t len = SCM_SIMPLE_VECTOR_LENGTH (obj);
         size_t i = depth / 2;
         unsigned long h = scm_raw_ihashq (SCM_CELL_WORD_0 (obj));
-        while (i--)
-          h ^= scm_raw_ihash (scm_c_vector_ref (obj, h % len), i);
+        if (len)
+          while (i--)
+            h ^= scm_raw_ihash (scm_c_vector_ref (obj, h % len), i);
         return h;
       }
     case scm_tcs_cons_imcar: