diff --git a/include/maxscale/filter.hh b/include/maxscale/filter.hh
index 278e39b0f..b39c63873 100644
--- a/include/maxscale/filter.hh
+++ b/include/maxscale/filter.hh
@@ -220,7 +220,7 @@ public:
     static MXS_FILTER_SESSION* newSession(MXS_FILTER* pInstance, MXS_SESSION* pSession)
     {
         FilterType* pFilter = static_cast<FilterType*>(pInstance);
-        FilterSessionType* pFilterSession;
+        FilterSessionType* pFilterSession = NULL;
 
         MXS_EXCEPTION_GUARD(pFilterSession = pFilter->newSession(pSession));
 
diff --git a/query_classifier/qc_sqlite/qc_sqlite.cc b/query_classifier/qc_sqlite/qc_sqlite.cc
index 4cfae297b..c4799a70c 100644
--- a/query_classifier/qc_sqlite/qc_sqlite.cc
+++ b/query_classifier/qc_sqlite/qc_sqlite.cc
@@ -4259,7 +4259,7 @@ static int32_t qc_sqlite_process_init(void)
         {
             if (this_unit.log_level != QC_LOG_NOTHING)
             {
-                const char* message;
+                const char* message = NULL;
 
                 switch (this_unit.log_level)
                 {
diff --git a/server/core/buffer.cc b/server/core/buffer.cc
index dfb9a865f..80d98a2f4 100644
--- a/server/core/buffer.cc
+++ b/server/core/buffer.cc
@@ -546,8 +546,8 @@ int gwbuf_compare(const GWBUF* lhs, const GWBUF* rhs)
 
             while ((rv == 0) && (i < llen))
             {
-                uint8_t lc;
-                uint8_t rc;
+                uint8_t lc = 0;
+                uint8_t rc = 0;
 
                 ss_debug(bool rv1 = ) gwbuf_get_byte(&lhs, &loffset, &lc);
                 ss_debug(bool rv2 = ) gwbuf_get_byte(&rhs, &roffset, &rc);
diff --git a/server/core/externcmd.cc b/server/core/externcmd.cc
index a922dc6fd..6e1a998fd 100644
--- a/server/core/externcmd.cc
+++ b/server/core/externcmd.cc
@@ -37,7 +37,7 @@ int tokenize_arguments(char* argstr, char** argv)
     bool escaped = false;
     char *ptr, *start;
     char args[strlen(argstr) + 1];
-    char qc;
+    char qc = 0;
 
     strcpy(args, argstr);
     start = args;
diff --git a/server/core/log_manager.cc b/server/core/log_manager.cc
index e5169f74c..a55e3196e 100644
--- a/server/core/log_manager.cc
+++ b/server/core/log_manager.cc
@@ -755,11 +755,11 @@ static int logmanager_write_log(int            priority,
                                 size_t         str_len,
                                 const char*    str)
 {
-    logfile_t*   lf;
-    char*        wp;
+    logfile_t*   lf = NULL;
+    char*        wp = NULL;
     int          err = 0;
-    blockbuf_t*  bb;
-    blockbuf_t*  bb_c;
+    blockbuf_t*  bb = NULL;
+    blockbuf_t*  bb_c = NULL;
     size_t       timestamp_len;
     int          i;
 
diff --git a/server/core/modutil.cc b/server/core/modutil.cc
index 8b5f7558a..978be9af3 100644
--- a/server/core/modutil.cc
+++ b/server/core/modutil.cc
@@ -762,7 +762,7 @@ char* strnchr_esc(char* ptr, char c, int len)
     char* p = (char*)ptr;
     char* start = p;
     bool quoted = false, escaped = false;
-    char qc;
+    char qc = 0;
 
     while (p < start + len)
     {
@@ -808,7 +808,7 @@ char* strnchr_esc_mysql(char* ptr, char c, int len)
     char* p = (char*) ptr;
     char* start = p, *end = start + len;
     bool quoted = false, escaped = false, backtick = false, comment = false;
-    char qc;
+    char qc = 0;
 
     while (p < end)
     {
diff --git a/server/core/server.cc b/server/core/server.cc
index c5458bc24..570efa4f0 100644
--- a/server/core/server.cc
+++ b/server/core/server.cc
@@ -933,9 +933,9 @@ serverRowCallback(RESULTSET *set, void *data)
 {
     int *rowno = (int *)data;
     int i = 0;
-    char *stat, buf[20];
-    RESULT_ROW *row;
-    SERVER *server;
+    char *stat = NULL, buf[20];
+    RESULT_ROW *row = NULL;
+    SERVER *server = NULL;
 
     spinlock_acquire(&server_spin);
     server = allServers;
diff --git a/server/core/service.cc b/server/core/service.cc
index e897303db..264b39126 100644
--- a/server/core/service.cc
+++ b/server/core/service.cc
@@ -1237,8 +1237,8 @@ void service_set_retry_interval(SERVICE *service, int value)
 bool
 serviceSetFilters(SERVICE *service, char *filters)
 {
-    MXS_FILTER_DEF **flist;
-    char *ptr, *brkt;
+    MXS_FILTER_DEF **flist = NULL;
+    char *ptr = NULL, *brkt = NULL;
     int n = 0;
     bool rval = true;
     uint64_t capabilities = 0;
diff --git a/server/core/utils.cc b/server/core/utils.cc
index 5a4381746..6b96c5ff0 100644
--- a/server/core/utils.cc
+++ b/server/core/utils.cc
@@ -989,7 +989,7 @@ int open_network_socket(enum mxs_socket_type type, struct sockaddr_storage *addr
 {
     ss_dassert(type == MXS_SOCKET_NETWORK || type == MXS_SOCKET_LISTENER);
     struct addrinfo *ai = NULL, hint = {};
-    int so, rc;
+    int so = 0, rc = 0;
     hint.ai_socktype = SOCK_STREAM;
     hint.ai_family = AF_UNSPEC;
     hint.ai_flags = AI_ALL;
diff --git a/server/modules/filter/cache/rules.cc b/server/modules/filter/cache/rules.cc
index 84f964c3c..35a4e3c6e 100644
--- a/server/modules/filter/cache/rules.cc
+++ b/server/modules/filter/cache/rules.cc
@@ -594,11 +594,11 @@ static CACHE_RULE *cache_rule_create_simple_user(cache_rule_attribute_t attribut
                                                  const char            *cvalue,
                                                  uint32_t               debug)
 {
+    CACHE_RULE *rule = NULL;
+
     ss_dassert(attribute == CACHE_ATTRIBUTE_USER);
     ss_dassert((op == CACHE_OP_EQ) || (op == CACHE_OP_NEQ));
 
-    CACHE_RULE *rule = NULL;
-
     bool error = false;
     size_t len = strlen(cvalue);
 
@@ -909,7 +909,7 @@ static CACHE_RULE *cache_rule_create_simple(cache_rule_attribute_t attribute,
 {
     ss_dassert((op == CACHE_OP_EQ) || (op == CACHE_OP_NEQ));
 
-    CACHE_RULE *rule;
+    CACHE_RULE *rule = NULL;
 
     switch (attribute)
     {
@@ -1524,7 +1524,7 @@ static bool cache_rule_matches_table_regexp(CACHE_RULE *self,
     bool matches = false;
 
     int n;
-    char **names;
+    char **names = NULL;
     bool fullnames;
 
     fullnames = true;
@@ -1610,7 +1610,7 @@ static bool cache_rule_matches_table_simple(CACHE_RULE *self, const char *defaul
     }
 
     int n;
-    char **names;
+    char **names = NULL;
 
     names = qc_get_table_names((GWBUF*)query, &n, fullnames);
 
diff --git a/server/modules/filter/dbfwfilter/dbfwfilter.c b/server/modules/filter/dbfwfilter/dbfwfilter.c
index 9730d361a..6b89a69c1 100644
--- a/server/modules/filter/dbfwfilter/dbfwfilter.c
+++ b/server/modules/filter/dbfwfilter/dbfwfilter.c
@@ -1036,7 +1036,7 @@ char* get_regex_string(char** saved)
 {
     char *start = NULL, *ptr = *saved;
     bool escaped = false, quoted = false;
-    char delimiter;
+    char delimiter = 0;
     while (*ptr != '\0')
     {
         if (!escaped)
diff --git a/server/modules/routing/debugcli/debugcmd.c b/server/modules/routing/debugcli/debugcmd.c
index 06eaf2a02..fa6e6df2e 100644
--- a/server/modules/routing/debugcli/debugcmd.c
+++ b/server/modules/routing/debugcli/debugcmd.c
@@ -1760,7 +1760,7 @@ static struct
 static unsigned long
 convert_arg(char *arg, int arg_type)
 {
-    unsigned long rval;
+    unsigned long rval = 0;
 
     switch (arg_type)
     {