diff --git a/include/maxscale/modulecmd.h b/include/maxscale/modulecmd.h
index fef3433c4..42c023d52 100644
--- a/include/maxscale/modulecmd.h
+++ b/include/maxscale/modulecmd.h
@@ -263,6 +263,6 @@ bool modulecmd_foreach(const char *domain_re, const char *ident_re,
  * @param type Type to convert
  * @return New string or NULL on memory allocation error
  */
-char* modulecmd_argtype_to_str(modulecmd_arg_type_t *type);
+const char* modulecmd_argtype_to_str(modulecmd_arg_type_t *type);
 
 MXS_END_DECLS
diff --git a/server/core/modulecmd.cc b/server/core/modulecmd.cc
index 456e8f57e..b0fbeeac8 100644
--- a/server/core/modulecmd.cc
+++ b/server/core/modulecmd.cc
@@ -625,50 +625,52 @@ bool modulecmd_foreach(const char *domain_re, const char *ident_re,
     return rval;
 }
 
-char* modulecmd_argtype_to_str(modulecmd_arg_type_t *type)
+#define format_type(a, b) (MODULECMD_ARG_IS_REQUIRED(a) ? b : "[" b "]")
+
+const char* modulecmd_argtype_to_str(modulecmd_arg_type_t *type)
 {
-    const char *strtype = "UNKNOWN";
+    const char* rval = "UNKNOWN";
 
     switch (MODULECMD_GET_TYPE(type))
     {
     case MODULECMD_ARG_NONE:
-        strtype = "NONE";
+        rval = format_type(type, "NONE");
         break;
 
     case MODULECMD_ARG_STRING:
-        strtype = "STRING";
+        rval = format_type(type, "STRING");
         break;
 
     case MODULECMD_ARG_BOOLEAN:
-        strtype = "BOOLEAN";
+        rval = format_type(type, "BOOLEAN");
         break;
 
     case MODULECMD_ARG_SERVICE:
-        strtype = "SERVICE";
+        rval = format_type(type, "SERVICE");
         break;
 
     case MODULECMD_ARG_SERVER:
-        strtype = "SERVER";
+        rval = format_type(type, "SERVER");
         break;
 
     case MODULECMD_ARG_SESSION:
-        strtype = "SESSION";
+        rval = format_type(type, "SESSION");
         break;
 
     case MODULECMD_ARG_DCB:
-        strtype = "DCB";
+        rval = format_type(type, "DCB");
         break;
 
     case MODULECMD_ARG_MONITOR:
-        strtype = "MONITOR";
+        rval = format_type(type, "MONITOR");
         break;
 
     case MODULECMD_ARG_FILTER:
-        strtype = "FILTER";
+        rval = format_type(type, "FILTER");
         break;
 
     case MODULECMD_ARG_OUTPUT:
-        strtype = "OUTPUT";
+        rval = format_type(type, "OUTPUT");
         break;
 
     default:
@@ -677,16 +679,6 @@ char* modulecmd_argtype_to_str(modulecmd_arg_type_t *type)
         break;
     }
 
-    size_t slen = strlen(strtype);
-    size_t extra = MODULECMD_ARG_IS_REQUIRED(type) ? 0 : 2;
-    char *rval = (char*)MXS_MALLOC(slen + extra + 1);
-
-    if (rval)
-    {
-        const char *fmtstr = extra ? "[%s]" : "%s";
-        sprintf(rval, fmtstr, strtype);
-    }
-
     return rval;
 }
 
diff --git a/server/modules/routing/debugcli/debugcmd.c b/server/modules/routing/debugcli/debugcmd.c
index a04e17b25..6c2a8aac3 100644
--- a/server/modules/routing/debugcli/debugcmd.c
+++ b/server/modules/routing/debugcli/debugcmd.c
@@ -330,13 +330,9 @@ bool listfuncs_cb(const MODULECMD *cmd, void *data)
 
         if (MODULECMD_GET_TYPE(type) != MODULECMD_ARG_OUTPUT)
         {
-            char *t = modulecmd_argtype_to_str(&cmd->arg_types[i]);
-
-            if (t)
-            {
-                dcb_printf(dcb, "%s%s", t, i < cmd->arg_count_max - 1 ? " " : "");
-                MXS_FREE(t);
-            }
+            dcb_printf(dcb, "%s%s",
+                       modulecmd_argtype_to_str(&cmd->arg_types[i]),
+                       i < cmd->arg_count_max - 1 ? " " : "");
         }
     }
 
@@ -348,14 +344,9 @@ bool listfuncs_cb(const MODULECMD *cmd, void *data)
 
         if (MODULECMD_GET_TYPE(type) != MODULECMD_ARG_OUTPUT)
         {
-
-            char *t = modulecmd_argtype_to_str(&cmd->arg_types[i]);
-
-            if (t)
-            {
-                dcb_printf(dcb, "    %s - %s\n", t, cmd->arg_types[i].description);
-                MXS_FREE(t);
-            }
+            dcb_printf(dcb, "    %s - %s\n",
+                       modulecmd_argtype_to_str(&cmd->arg_types[i]),
+                       cmd->arg_types[i].description);
         }
     }