diff --git a/Documentation/Filters/Query-Log-All-Filter.md b/Documentation/Filters/Query-Log-All-Filter.md
index 892f4ad4e..ec9d5639b 100644
--- a/Documentation/Filters/Query-Log-All-Filter.md
+++ b/Documentation/Filters/Query-Log-All-Filter.md
@@ -43,11 +43,11 @@ anymore and the `filebase` parameter should be used instead.
 
 ## Filter Parameters
 
-The QLA filter accepts a number of optional parameters, these were introduced in the 1.0 release of MaxScale.
+The QLA filter has one mandatory parameter, `filebase`, and a number of optional parameters. These were introduced in the 1.0 release of MaxScale.
 
 ### Filebase
 
-The basename of the output file created for each session. A session index is added to the filename for each file written.
+The basename of the output file created for each session. A session index is added to the filename for each file written. This is a mandatory parameter.
 
 ```
 filebase=/tmp/SqlQueryLog
diff --git a/Documentation/Filters/Top-N-Filter.md b/Documentation/Filters/Top-N-Filter.md
index 5920d9c6d..978f23aba 100644
--- a/Documentation/Filters/Top-N-Filter.md
+++ b/Documentation/Filters/Top-N-Filter.md
@@ -40,11 +40,11 @@ options=case,extended
 
 ## Filter Parameters
 
-The top filter accepts a number of optional parameters.
+The top filter has one mandatory parameter, `filebase`, and a number of optional parameters.
 
 ### Filebase
 
-The basename of the output file created for each session. A session index is added to the filename for each file written.
+The basename of the output file created for each session. A session index is added to the filename for each file written. This is a mandatory parameter.
 
 ```
 filebase=/tmp/SqlQueryLog
diff --git a/server/modules/filter/namedserverfilter.c b/server/modules/filter/namedserverfilter.c
index e5e30a4e1..4156e7857 100644
--- a/server/modules/filter/namedserverfilter.c
+++ b/server/modules/filter/namedserverfilter.c
@@ -85,7 +85,6 @@ typedef struct
     char *user; /* User name to restrict matches */
     char *match; /* Regular expression to match */
     char *server; /* Server to route to */
-    int cflags; /* Regexec compile flags */
     regex_t re; /* Compiled regex text */
 } REGEXHINT_INSTANCE;
 
@@ -147,14 +146,17 @@ static FILTER *
 createInstance(char **options, FILTER_PARAMETER **params)
 {
     REGEXHINT_INSTANCE *my_instance;
-    int i, cflags = REG_ICASE;
+    int cflags = REG_ICASE;
 
-    if ((my_instance = calloc(1, sizeof(REGEXHINT_INSTANCE))) != NULL)
+    if ((my_instance = malloc(sizeof(REGEXHINT_INSTANCE))) != NULL)
     {
         my_instance->match = NULL;
         my_instance->server = NULL;
+        my_instance->source = NULL;
+        my_instance->user = NULL;
+        bool error = false;
 
-        for (i = 0; params && params[i]; i++)
+        for (int i = 0; params && params[i]; i++)
         {
             if (!strcmp(params[i]->name, "match"))
             {
@@ -176,12 +178,13 @@ createInstance(char **options, FILTER_PARAMETER **params)
             {
                 MXS_ERROR("namedserverfilter: Unexpected parameter '%s'.",
                           params[i]->name);
+                error = true;
             }
         }
 
         if (options)
         {
-            for (i = 0; options[i]; i++)
+            for (int i = 0; options[i]; i++)
             {
                 if (!strcasecmp(options[i], "ignorecase"))
                 {
@@ -197,32 +200,48 @@ createInstance(char **options, FILTER_PARAMETER **params)
                 }
                 else
                 {
-                    MXS_ERROR("namedserverfilter: unsupported option '%s'.",
+                    MXS_ERROR("namedserverfilter: Unsupported option '%s'.",
                               options[i]);
+                    error = true;
                 }
             }
         }
-        my_instance->cflags = cflags;
 
-        if (my_instance->match == NULL || my_instance->server == NULL)
+        if (my_instance->match == NULL)
         {
-            MXS_ERROR("namedserverfilter: Missing required configured"
-                      " option. You must specify a match and server "
-                      "option as a minimum.");
-            free(my_instance);
-            return NULL;
+            MXS_ERROR("namedserverfilter: Missing required parameters 'match'.");
+            error = true;
         }
 
-        if (regcomp(&my_instance->re, my_instance->match,
-                    my_instance->cflags))
+        if (my_instance->server == NULL)
+        {
+            MXS_ERROR("namedserverfilter: Missing required parameters 'server'.");
+            error = true;
+        }
+        if (my_instance->server && my_instance->match &&
+            regcomp(&my_instance->re, my_instance->match, cflags))
         {
             MXS_ERROR("namedserverfilter: Invalid regular expression '%s'.\n",
                       my_instance->match);
             free(my_instance->match);
-            free(my_instance->server);
-            free(my_instance);
-            return NULL;
+            my_instance->match = NULL;
+            error = true;
         }
+
+        if (error)
+        {
+            if (my_instance->match)
+            {
+                regfree(&my_instance->re);
+                free(my_instance->match);
+            }
+            free(my_instance->server);
+            free(my_instance->source);
+            free(my_instance->user);
+            free(my_instance);
+            my_instance = NULL;
+        }
+
     }
     return(FILTER *) my_instance;
 }
diff --git a/server/modules/filter/qlafilter.c b/server/modules/filter/qlafilter.c
index 241548959..9be4ba21a 100644
--- a/server/modules/filter/qlafilter.c
+++ b/server/modules/filter/qlafilter.c
@@ -175,12 +175,15 @@ createInstance(char **options, FILTER_PARAMETER **params)
     QLA_INSTANCE *my_instance;
     int i;
 
-    if ((my_instance = calloc(1, sizeof(QLA_INSTANCE))) != NULL)
+    if ((my_instance = malloc(sizeof(QLA_INSTANCE))) != NULL)
     {
         my_instance->source = NULL;
         my_instance->userName = NULL;
         my_instance->match = NULL;
         my_instance->nomatch = NULL;
+        my_instance->filebase = NULL;
+        bool error = false;
+
         if (params)
         {
             for (i = 0; params[i]; i++)
@@ -203,17 +206,13 @@ createInstance(char **options, FILTER_PARAMETER **params)
                 }
                 else if (!strcmp(params[i]->name, "filebase"))
                 {
-                    if (my_instance->filebase)
-                    {
-                        free(my_instance->filebase);
-                        my_instance->filebase = NULL;
-                    }
                     my_instance->filebase = strdup(params[i]->value);
                 }
                 else if (!filter_standard_parameter(params[i]->name))
                 {
                     MXS_ERROR("qlafilter: Unexpected parameter '%s'.",
                               params[i]->name);
+                    error = true;
                 }
             }
         }
@@ -238,46 +237,59 @@ createInstance(char **options, FILTER_PARAMETER **params)
                 }
                 else
                 {
-                    MXS_ERROR("qlafilter: unsupported option '%s'.",
+                    MXS_ERROR("qlafilter: Unsupported option '%s'.",
                               options[i]);
+                    error = true;
                 }
             }
         }
 
+        if (my_instance->filebase == NULL)
+        {
+            MXS_ERROR("qlafilter: No 'filebase' parameter defined.");
+            error = true;
+        }
+
         my_instance->sessions = 0;
         if (my_instance->match &&
             regcomp(&my_instance->re, my_instance->match, cflags))
         {
             MXS_ERROR("qlafilter: Invalid regular expression '%s'"
-                      " for the match parameter.\n",
+                      " for the 'match' parameter.\n",
                       my_instance->match);
             free(my_instance->match);
-            free(my_instance->source);
-            if (my_instance->filebase)
-            {
-                free(my_instance->filebase);
-            }
-            free(my_instance);
-            return NULL;
+            my_instance->match = NULL;
+            error = true;
         }
         if (my_instance->nomatch &&
             regcomp(&my_instance->nore, my_instance->nomatch, cflags))
         {
             MXS_ERROR("qlafilter: Invalid regular expression '%s'"
-                      " for the nomatch paramter.",
-                      my_instance->match);
+                      " for the 'nomatch' parameter.",
+                      my_instance->nomatch);
+            free(my_instance->nomatch);
+            my_instance->nomatch = NULL;
+            error = true;
+        }
+
+        if (error)
+        {
             if (my_instance->match)
             {
+                free(my_instance->match);
                 regfree(&my_instance->re);
             }
-            free(my_instance->match);
-            free(my_instance->source);
-            if (my_instance->filebase)
+
+            if (my_instance->match)
             {
-                free(my_instance->filebase);
+                free(my_instance->match);
+                regfree(&my_instance->re);
             }
+            free(my_instance->filebase);
+            free(my_instance->source);
+            free(my_instance->userName);
             free(my_instance);
-            return NULL;
+            my_instance = NULL;
         }
     }
     return(FILTER *) my_instance;
diff --git a/server/modules/filter/topfilter.c b/server/modules/filter/topfilter.c
index 6b40713f0..87cff29dd 100644
--- a/server/modules/filter/topfilter.c
+++ b/server/modules/filter/topfilter.c
@@ -176,7 +176,6 @@ GetModuleObject()
 {
     return &MyObject;
 }
-
 /**
  * Create an instance of the filter for a particular service
  * within MaxScale.
@@ -192,14 +191,16 @@ createInstance(char **options, FILTER_PARAMETER **params)
     int i;
     TOPN_INSTANCE *my_instance;
 
-    if ((my_instance = calloc(1, sizeof(TOPN_INSTANCE))) != NULL)
+    if ((my_instance = malloc(sizeof(TOPN_INSTANCE))) != NULL)
     {
         my_instance->topN = 10;
         my_instance->match = NULL;
         my_instance->exclude = NULL;
         my_instance->source = NULL;
         my_instance->user = NULL;
-        my_instance->filebase = strdup("top");
+        my_instance->filebase = NULL;
+        bool error = false;
+
         for (i = 0; params && params[i]; i++)
         {
             if (!strcmp(params[i]->name, "count"))
@@ -208,7 +209,6 @@ createInstance(char **options, FILTER_PARAMETER **params)
             }
             else if (!strcmp(params[i]->name, "filebase"))
             {
-                free(my_instance->filebase);
                 my_instance->filebase = strdup(params[i]->value);
             }
             else if (!strcmp(params[i]->name, "match"))
@@ -231,6 +231,7 @@ createInstance(char **options, FILTER_PARAMETER **params)
             {
                 MXS_ERROR("topfilter: Unexpected parameter '%s'.",
                           params[i]->name);
+                error = true;
             }
         }
 
@@ -254,39 +255,60 @@ createInstance(char **options, FILTER_PARAMETER **params)
                 }
                 else
                 {
-                    MXS_ERROR("topfilter: unsupported option '%s'.",
+                    MXS_ERROR("topfilter: Unsupported option '%s'.",
                               options[i]);
+                    error = true;
                 }
             }
         }
 
+        if (my_instance->filebase == NULL)
+        {
+            MXS_ERROR("topfilter: No 'filebase' parameter defined.");
+            error = true;
+        }
+
         my_instance->sessions = 0;
         if (my_instance->match &&
             regcomp(&my_instance->re, my_instance->match, cflags))
         {
             MXS_ERROR("topfilter: Invalid regular expression '%s'"
-                      " for the match parameter.",
+                      " for the 'match' parameter.",
                       my_instance->match);
+            regfree(&my_instance->re);
             free(my_instance->match);
-            free(my_instance->source);
-            free(my_instance->user);
-            free(my_instance->filebase);
-            free(my_instance);
-            return NULL;
+            my_instance->match = NULL;
+            error = true;
         }
         if (my_instance->exclude &&
             regcomp(&my_instance->exre, my_instance->exclude, cflags))
         {
-            MXS_ERROR("qlafilter: Invalid regular expression '%s'"
-                      " for the nomatch paramter.\n",
-                      my_instance->match);
-            regfree(&my_instance->re);
-            free(my_instance->match);
+            MXS_ERROR("topfilter: Invalid regular expression '%s'"
+                      " for the 'nomatch' parameter.\n",
+                      my_instance->exclude);
+            regfree(&my_instance->exre);
+            free(my_instance->exclude);
+            my_instance->exclude = NULL;
+            error = true;
+        }
+
+        if (error)
+        {
+            if (my_instance->exclude)
+            {
+                regfree(&my_instance->exre);
+                free(my_instance->exclude);
+            }
+            if (my_instance->match)
+            {
+                regfree(&my_instance->re);
+                free(my_instance->match);
+            }
+            free(my_instance->filebase);
             free(my_instance->source);
             free(my_instance->user);
-            free(my_instance->filebase);
             free(my_instance);
-            return NULL;
+            my_instance = NULL;
         }
     }
     return(FILTER *) my_instance;