Index: PGConnection.m
==================================================================
--- PGConnection.m
+++ PGConnection.m
@@ -103,12 +103,12 @@
 				     count: argsCount];
 	@try {
 		size_t i = 0;
 
 		do {
-			if ([parameter isKindOfClass: [OFNull class]])
-				values[i++] = NULL;
+			if ([parameter isKindOfClass: [OFString class]])
+				values[i++] = [parameter UTF8String];
 			else if ([parameter isKindOfClass: [OFNumber class]]) {
 				switch ([parameter type]) {
 				case OF_NUMBER_BOOL:
 					if ([parameter boolValue])
 						values[i++] = "t";
@@ -118,12 +118,15 @@
 				default:
 					values[i++] = [[parameter description]
 					    UTF8String];
 					break;
 				}
-			} else
-				values[i++] = [parameter UTF8String];
+			} else if ([parameter isKindOfClass: [OFNull class]])
+				values[i++] = NULL;
+			else
+				values[i++] = [[parameter description]
+				    UTF8String];
 		} while ((parameter = va_arg(args, id)) != nil);
 
 		result = PQexecParams(conn, [command UTF8String],
 		    argsCount, NULL, values, NULL, NULL, 0);
 	} @finally {