diff --git a/src/message_test.c b/src/message_test.c
index 41b8875..ec231e8e 100644
--- a/src/message_test.c
+++ b/src/message_test.c
@@ -28,37 +28,69 @@
     static void
 test_trunc_string(void)
 {
-    char_u  buf[40];
+    char_u  *buf; /*allocated every time to find uninit errors */
+    char_u  *s;
 
     /* in place */
+    buf = alloc(40);
     STRCPY(buf, "text");
     trunc_string(buf, buf, 20, 40);
     assert(STRCMP(buf, "text") == 0);
+    vim_free(buf);
 
+    buf = alloc(40);
     STRCPY(buf, "a short text");
     trunc_string(buf, buf, 20, 40);
     assert(STRCMP(buf, "a short text") == 0);
+    vim_free(buf);
 
+    buf = alloc(40);
     STRCPY(buf, "a text tha just fits");
     trunc_string(buf, buf, 20, 40);
     assert(STRCMP(buf, "a text tha just fits") == 0);
+    vim_free(buf);
 
+    buf = alloc(40);
     STRCPY(buf, "a text that nott fits");
     trunc_string(buf, buf, 20, 40);
     assert(STRCMP(buf, "a text t...nott fits") == 0);
+    vim_free(buf);
 
     /* copy from string to buf */
-    trunc_string((char_u *)"text", buf, 20, 40);
+    buf = alloc(40);
+    s = vim_strsave((char_u *)"text");
+    trunc_string(s, buf, 20, 40);
     assert(STRCMP(buf, "text") == 0);
+    vim_free(buf);
+    vim_free(s);
 
-    trunc_string((char_u *)"a short text", buf, 20, 40);
+    buf = alloc(40);
+    s = vim_strsave((char_u *)"a text that fits");
+    trunc_string(s, buf, 34, 40);
+    assert(STRCMP(buf, "a text that fits") == 0);
+    vim_free(buf);
+    vim_free(s);
+
+    buf = alloc(40);
+    s = vim_strsave((char_u *)"a short text");
+    trunc_string(s, buf, 20, 40);
     assert(STRCMP(buf, "a short text") == 0);
+    vim_free(buf);
+    vim_free(s);
 
-    trunc_string((char_u *)"a text tha just fits", buf, 20, 40);
+    buf = alloc(40);
+    s = vim_strsave((char_u *)"a text tha just fits");
+    trunc_string(s, buf, 20, 40);
     assert(STRCMP(buf, "a text tha just fits") == 0);
+    vim_free(buf);
+    vim_free(s);
 
-    trunc_string((char_u *)"a text that nott fits", buf, 20, 40);
+    buf = alloc(40);
+    s = vim_strsave((char_u *)"a text that nott fits");
+    trunc_string(s, buf, 20, 40);
     assert(STRCMP(buf, "a text t...nott fits") == 0);
+    vim_free(buf);
+    vim_free(s);
 }
 
     int