@@ -1,26 +1,31 @@
 #include <libpq-fe.h>
 
 #import <ObjFW/ObjFW.h>
 
 #import "PGResult.h"
+
+OF_ASSUME_NONNULL_BEGIN
 
 @interface PGConnection: OFObject
 {
 	PGconn *_connnection;
-	OFDictionary *_parameters;
+	OFDictionary OF_GENERIC(OFString *, OFString *) *_parameters;
 }
 
-@property (copy) OFDictionary *parameters;
+@property (nonatomic, copy)
+    OFDictionary OF_GENERIC(OFString *, OFString *) *parameters;
 
 - (void)connect;
 - (void)reset;
 - (void)close;
-- (PGResult*)executeCommand: (OFConstantString*)command;
-- (PGResult*)executeCommand: (OFConstantString*)command
-		 parameters: (id)firstParameter, ... OF_SENTINEL;
-- (PGconn*)PG_connection;
-- (void)insertRow: (OFDictionary*)row
-	intoTable: (OFString*)table;
-- (void)insertRows: (OFArray*)rows
-	 intoTable: (OFString*)table;
+- (PGResult *)executeCommand: (OFConstantString *)command;
+- (PGResult *)executeCommand: (OFConstantString *)command
+		  parameters: (id)firstParameter, ... OF_SENTINEL;
+- (PGconn *)PG_connection;
+- (void)insertRow: (OFDictionary *)row
+	intoTable: (OFString *)table;
+- (void)insertRows: (OFArray OF_GENERIC(OFDictionary *) *)rows
+	 intoTable: (OFString *)table;
 @end
+
+OF_ASSUME_NONNULL_END