diff --git a/src/common/DynamicStrings.cpp b/src/common/DynamicStrings.cpp
index 72be2e07ae6..1e02df3e874 100644
--- a/src/common/DynamicStrings.cpp
+++ b/src/common/DynamicStrings.cpp
@@ -87,6 +87,8 @@ unsigned makeDynamicStrings(unsigned length, ISC_STATUS* const dst, const ISC_ST
 		case isc_arg_cstring:
 			fb_assert(string);
 			*to++ = (ISC_STATUS)(IPTR) string;
+			if (!string)
+				break;
 			memcpy(string, reinterpret_cast<const char*>(from[1]), from[0]);
 			string += *from++;
 			*string++ = '\0';
@@ -97,6 +99,8 @@ unsigned makeDynamicStrings(unsigned length, ISC_STATUS* const dst, const ISC_ST
 		case isc_arg_sql_state:
 			fb_assert(string);
 			*to++ = (ISC_STATUS)(IPTR) string;
+			if (!string)
+				break;
 			strcpy(string, reinterpret_cast<const char*>(*from));
 			string += strlen(string);
 			string++;
diff --git a/src/dsql/DdlNodes.epp b/src/dsql/DdlNodes.epp
index 3af5163719b..584ab90fca2 100644
--- a/src/dsql/DdlNodes.epp
+++ b/src/dsql/DdlNodes.epp
@@ -345,7 +345,7 @@ void defineComputed(DsqlCompilerScratch* dsqlScratch, RelationSourceNode* relati
 	// Save the size of the field if it is specified.
 	dsc saveDesc;
 	saveDesc.dsc_dtype = 0;
-	bool saveCharSetIdSpecified;
+	bool saveCharSetIdSpecified = false;
 
 	if (field && field->dtype)
 	{
diff --git a/src/gpre/c_cxx.cpp b/src/gpre/c_cxx.cpp
index e5a5025dddc..c3b10bf1e32 100644
--- a/src/gpre/c_cxx.cpp
+++ b/src/gpre/c_cxx.cpp
@@ -2668,6 +2668,8 @@ static void gen_put_segment( const act* action, int column)
 	args.pat_ident1 = blob->blb_len_ident;
 	args.pat_ident2 = blob->blb_buff_ident;
 	args.pat_string1 = global_status_name;
+	args.pat_long1 = NULL;
+	args.pat_long2 = NULL;
 	PATTERN_expand((USHORT) column, pattern1, &args);
 
 	set_sqlcode(action, column);
diff --git a/src/gpre/obj_cxx.cpp b/src/gpre/obj_cxx.cpp
index b863f2cf3e6..aae53bdc94f 100644
--- a/src/gpre/obj_cxx.cpp
+++ b/src/gpre/obj_cxx.cpp
@@ -3368,7 +3368,8 @@ static void gen_t_start( const act* action, int column)
 
 	if (trans->tra_db_count == 1)
 	{
-		printa(column, "%s = %s->startTransaction(%s, %d, fb_tpb_%d);",
+		if (trans->tra_tpb) 
+			printa(column, "%s = %s->startTransaction(%s, %d, fb_tpb_%d);",
 			trans->tra_handle ? trans->tra_handle : gpreGlob.transaction_name,
 			trans->tra_tpb->tpb_database->dbb_name->sym_string, vector,
 			trans->tra_tpb->tpb_length, trans->tra_tpb->tpb_ident);
diff --git a/src/gpre/pat.cpp b/src/gpre/pat.cpp
index 817ae409765..e8b43e99adb 100644
--- a/src/gpre/pat.cpp
+++ b/src/gpre/pat.cpp
@@ -364,12 +364,14 @@ void PATTERN_expand( USHORT column, const TEXT* pattern, PAT* args)
 			break;
 
 		case L1:
-			long_value = args->pat_long1;
+			if (args && args->pat_long1) 
+				long_value = args->pat_long1;
 			long_flag = true;
 			break;
 
 		case L2:
-			long_value = args->pat_long2;
+			if (args && args->pat_long2) 
+				long_value = args->pat_long2;
 			long_flag = true;
 			break;
 
diff --git a/src/jrd/IntlManager.cpp b/src/jrd/IntlManager.cpp
index 0c5a29048c6..716ec37941d 100644
--- a/src/jrd/IntlManager.cpp
+++ b/src/jrd/IntlManager.cpp
@@ -458,11 +458,11 @@ bool IntlManager::initialize()
 				string configInfo;
 
 				const ConfigFile::Parameter* module = ch->sub->findParameter("intl_module");
-				const ConfigFile::Parameter* objModule;
+				const ConfigFile::Parameter* objModule = NULL;
 				if (module &&
 					(objModule = configFile.findParameter("intl_module", module->value.c_str())))
 				{
-					if (!objModule->sub)
+					if (!objModule || !objModule->sub)
 						fatal_exception::raiseFmt("Missing parameters for intl_module %s\n", module->value.c_str());
 
 					const ConfigFile::Parameter* fname = objModule->sub->findParameter("filename");
diff --git a/src/jrd/cvt2.cpp b/src/jrd/cvt2.cpp
index 60be2939844..e61c5d8d07a 100644
--- a/src/jrd/cvt2.cpp
+++ b/src/jrd/cvt2.cpp
@@ -767,7 +767,7 @@ int CVT2_blob_compare(const dsc* arg1, const dsc* arg2, DecimalStatus decSt)
  *
  **************************************/
 
-	SLONG l1, l2;
+	SLONG l1 = NULL, l2 = NULL;
 	USHORT ttype2;
 	int ret_val = 0;
 
diff --git a/src/jrd/lck.cpp b/src/jrd/lck.cpp
index 8a3baf6bf8d..89f30736a78 100644
--- a/src/jrd/lck.cpp
+++ b/src/jrd/lck.cpp
@@ -1049,6 +1049,9 @@ static Lock* hash_get_lock(Lock* lock, USHORT* hash_slot, Lock*** prior)
 
 	// if no collisions found, we're done
 
+	if (!att->att_compatibility_table)
+		return NULL;
+
 	Lock* match = (*att->att_compatibility_table)[hash_value];
 	if (!match)
 		return NULL;
@@ -1333,6 +1336,9 @@ static USHORT internal_downgrade(thread_db* tdbb, CheckStatusWrapper* statusVect
 
 	// if we can convert to that level, set all identical locks as having that level
 
+	if (!first || !first->lck_physical)
+		return NULL;
+	
 	if (level < first->lck_physical)
 	{
 		if (dbb->lockManager()->convert(tdbb, statusVector, first->lck_id, level, LCK_NO_WAIT,
diff --git a/src/jrd/replication/Applier.cpp b/src/jrd/replication/Applier.cpp
index c9e9f39419a..6a47bba47bd 100644
--- a/src/jrd/replication/Applier.cpp
+++ b/src/jrd/replication/Applier.cpp
@@ -998,10 +998,12 @@ void Applier::storeBlob(thread_db* tdbb, TraNumber traNum, bid* blobId,
 	fb_assert(blob->blb_flags & BLB_temporary);
 	fb_assert(!(blob->blb_flags & BLB_closed));
 
-	if (length)
-		blob->BLB_put_segment(tdbb, data, length);
-	else
-		blob->BLB_close(tdbb);
+	if (blob){
+		if (length)
+			blob->BLB_put_segment(tdbb, data, length);
+		else
+			blob->BLB_close(tdbb);
+	}
 }
 
 void Applier::executeSql(thread_db* tdbb,
diff --git a/src/remote/server/server.cpp b/src/remote/server/server.cpp
index 6cea42401fa..c107d23b3c5 100644
--- a/src/remote/server/server.cpp
+++ b/src/remote/server/server.cpp
@@ -6129,10 +6129,10 @@ bool rem_port::sendInlineBlob(PACKET* sendL, Rtr* rtr, SQUAD blobId, ULONG maxSi
 	if (status.getState() & IStatus::STATE_ERRORS)
 		return false;
 
-	bool segmented;
+	bool segmented = false;
 	ULONG num_segments;
 	ULONG max_segment;
-	FB_UINT64 total_length;
+	FB_UINT64 total_length = 0u;
 
 	ClumpletReader p(ClumpletReader::InfoResponse, info, sizeof(info));
 	for (; !p.isEof(); p.moveNext())