diff --git a/src/utils.c b/src/utils.c
index d3e5787..094a748 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -78,6 +78,8 @@ char *string_append(char *a, const char *b, const char *sep)
 {
         if (!a)
                 return g_strdup(b);
+        if (!b)
+                return a;
 
         char *new;
         if (!sep)
diff --git a/test/utils.c b/test/utils.c
index bccdd60..6fcee97 100644
--- a/test/utils.c
+++ b/test/utils.c
@@ -91,6 +91,8 @@ TEST test_string_append(void)
 
         ASSERT_STR_EQ("a", (exp = string_append(g_strdup("a"), "", NULL)));
         g_free(exp);
+        ASSERT_STR_EQ("a", (exp = string_append(g_strdup("a"), NULL, "_sep_")));
+        g_free(exp);
 
         ASSERT_EQ(NULL, (exp = string_append(NULL, NULL, "_sep_")));
         g_free(exp);