diff --git a/m-string.h b/m-string.h
index 12781dc4..80bebb29 100644
--- a/m-string.h
+++ b/m-string.h
@@ -552,8 +552,11 @@ string_fgets(string_t v, FILE *f, string_fgets_t arg)
       }
       STRING_CONTRACT(v);
       return;
-    } else if (p == NULL)
+    } else if (p == NULL && !feof(f)) {
+      /* The string buffer is not big enough:
+         increase it and continue reading */
       stringi_fit2size (v, v->alloc + v->alloc/2);
+    }
   }
   STRING_CONTRACT (v);
 }