diff --git a/include/osmocom/core/sockaddr_str.h b/include/osmocom/core/sockaddr_str.h
index d47b2a4..6dd428c 100644
--- a/include/osmocom/core/sockaddr_str.h
+++ b/include/osmocom/core/sockaddr_str.h
@@ -61,8 +61,12 @@
  *     struct osmo_sockaddr_str *my_sockaddr_str = ...;
  *     printf("got " OSMO_SOCKADDR_STR_FMT "\n", OSMO_SOCKADDR_STR_FMT_ARGS(my_sockaddr_str));
  */
-#define OSMO_SOCKADDR_STR_FMT "%s:%u"
-#define OSMO_SOCKADDR_STR_FMT_ARGS(R) ((R)? (R)->ip : "NULL"), ((R)? (R)->port : 0)
+#define OSMO_SOCKADDR_STR_FMT "%s%s%s:%u"
+#define OSMO_SOCKADDR_STR_FMT_ARGS(R) \
+	((R) && (R)->af == AF_INET6)? "[" : "", \
+	(R)? (R)->ip : "NULL", \
+	((R) && (R)->af == AF_INET6)? "]" : "", \
+	(R)? (R)->port : 0
 
 bool osmo_sockaddr_str_is_set(const struct osmo_sockaddr_str *sockaddr_str);
 bool osmo_sockaddr_str_is_nonzero(const struct osmo_sockaddr_str *sockaddr_str);
diff --git a/tests/sockaddr_str/sockaddr_str_test.ok b/tests/sockaddr_str/sockaddr_str_test.ok
index 5ebf7be..bc18225 100644
--- a/tests/sockaddr_str/sockaddr_str_test.ok
+++ b/tests/sockaddr_str/sockaddr_str_test.ok
@@ -86,7 +86,7 @@
 
 
 { .af = AF_INET6, .ip = "1:2:3::4", .port = 5 }
-  OSMO_SOCKADDR_STR_FMT: '1:2:3::4:5'
+  OSMO_SOCKADDR_STR_FMT: '[1:2:3::4]:5'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = true
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -103,7 +103,7 @@
 
 
 { .af = AF_INET6, .ip = "::", .port = 0 }
-  OSMO_SOCKADDR_STR_FMT: ':::0'
+  OSMO_SOCKADDR_STR_FMT: '[::]:0'
   osmo_sockaddr_str_is_set() = false
   osmo_sockaddr_str_is_nonzero() = false
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -120,7 +120,7 @@
 
 
 { .af = AF_INET6, .ip = "::1", .port = 0 }
-  OSMO_SOCKADDR_STR_FMT: '::1:0'
+  OSMO_SOCKADDR_STR_FMT: '[::1]:0'
   osmo_sockaddr_str_is_set() = false
   osmo_sockaddr_str_is_nonzero() = false
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -137,7 +137,7 @@
 
 
 { .af = AF_INET6, .ip = "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff", .port = 65535 }
-  OSMO_SOCKADDR_STR_FMT: 'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff:65535'
+  OSMO_SOCKADDR_STR_FMT: '[ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff]:65535'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = true
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -154,7 +154,7 @@
 
 
 { .af = AF_INET6, .ip = "FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF", .port = 65535 }
-  OSMO_SOCKADDR_STR_FMT: 'FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:65535'
+  OSMO_SOCKADDR_STR_FMT: '[FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF]:65535'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = true
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -174,7 +174,7 @@
 
 
 { .af = AF_INET6, .ip = "::fffff", .port = 1 }
-  OSMO_SOCKADDR_STR_FMT: '::fffff:1'
+  OSMO_SOCKADDR_STR_FMT: '[::fffff]:1'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = false
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -188,7 +188,7 @@
 
 
 { .af = AF_INET6, .ip = "not an ip address", .port = 1 }
-  OSMO_SOCKADDR_STR_FMT: 'not an ip address:1'
+  OSMO_SOCKADDR_STR_FMT: '[not an ip address]:1'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = false
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -202,7 +202,7 @@
 
 
 { .af = AF_INET6, .ip = "1.2.3.4", .port = 5 }
-  OSMO_SOCKADDR_STR_FMT: '1.2.3.4:5'
+  OSMO_SOCKADDR_STR_FMT: '[1.2.3.4]:5'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = false
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -261,7 +261,7 @@
 
 
 { .af = AF_INET6, .ip = "", .port = 5 }
-  OSMO_SOCKADDR_STR_FMT: ':5'
+  OSMO_SOCKADDR_STR_FMT: '[]:5'
   osmo_sockaddr_str_is_set() = false
   osmo_sockaddr_str_is_nonzero() = false
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -309,7 +309,7 @@
 
 
 { .af = AF_INET6, .ip = "::1:10.9.8.7", .port = 1 }
-  OSMO_SOCKADDR_STR_FMT: '::1:10.9.8.7:1'
+  OSMO_SOCKADDR_STR_FMT: '[::1:10.9.8.7]:1'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = true
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000
@@ -348,7 +348,7 @@
 
 
 { .af = AF_INET6, .ip = "::", .port = 5 }
-  OSMO_SOCKADDR_STR_FMT: ':::5'
+  OSMO_SOCKADDR_STR_FMT: '[::]:5'
   osmo_sockaddr_str_is_set() = true
   osmo_sockaddr_str_is_nonzero() = false
   osmo_sockaddr_str_to_in_addr() rc < 0 in_addr=00000000