Index: Makefile
==================================================================
--- Makefile
+++ Makefile
@@ -32,10 +32,11 @@
 		--builddir build	\
 		${CPPFLAGS}		\
 		${LIBS}			\
 		${SRCS}
 
+.PHONY: test
 test:
 	@objfw-compile			\
 		-o test			\
 		--builddir build	\
 		-L.			\

Index: PGConnection.m
==================================================================
--- PGConnection.m
+++ PGConnection.m
@@ -97,11 +97,24 @@
 		size_t i = 0;
 
 		do {
 			if ([parameter isKindOfClass: [OFNull class]])
 				values[i++] = NULL;
-			else
+			else if ([parameter isKindOfClass: [OFNumber class]]) {
+				switch ([parameter type]) {
+				case OF_NUMBER_BOOL:
+					if ([parameter boolValue])
+						values[i++] = "t";
+					else
+						values[i++] = "f";
+					break;
+				default:
+					values[i++] = [[parameter description]
+					    UTF8String];
+					break;
+				}
+			} else
 				values[i++] = [parameter UTF8String];
 		} while ((parameter = va_arg(args, id)) != nil);
 
 		result = PQexecParams(conn, [command UTF8String],
 		    argsCount, NULL, values, NULL, NULL, 0);

Index: PGResultRow.m
==================================================================
--- PGResultRow.m
+++ PGResultRow.m
@@ -1,6 +1,26 @@
 #import "PGResultRow.h"
+
+static id
+convert_type(PGresult *res, int col, OFString *str)
+{
+	switch (PQftype(res, col)) {
+	case 16: /* BOOLOID */
+		if ([str isEqual: @"t"])
+			return [OFNumber numberWithBool: YES];
+		else
+			return [OFNumber numberWithBool: NO];
+	case 21: /* INT2OID */
+		return [OFNumber numberWithInt16: (int16_t)[str decimalValue]];
+	case 23: /* INT4OID */
+		return [OFNumber numberWithInt32: (int32_t)[str decimalValue]];
+	case 20: /* INT8OID */
+		return [OFNumber numberWithInt64: (int64_t)[str decimalValue]];
+	}
+
+	return str;
+}
 
 @interface PGResultRowEnumerator: OFEnumerator
 {
 	PGResult *result;
 	PGresult *res;
@@ -65,11 +85,12 @@
 		col = PQfnumber(res, [key UTF8String]);
 
 	if (PQgetisnull(res, row, col))
 		return nil;
 
-	return [OFString stringWithUTF8String: PQgetvalue(res, row, col)];
+	return convert_type(res, col,
+	    [OFString stringWithUTF8String: PQgetvalue(res, row, col)]);
 }
 
 - (OFEnumerator*)keyEnumerator
 {
 	return [[[PGResultRowKeyEnumerator alloc]
@@ -131,8 +152,9 @@
 		pos++;
 
 	if (pos >= count)
 		return nil;
 
-	return [OFString stringWithUTF8String: PQgetvalue(res, row, pos++)];
+	return convert_type(res, pos,
+	    [OFString stringWithUTF8String: PQgetvalue(res, row, pos++)]);
 }
 @end

Index: test.m
==================================================================
--- test.m
+++ test.m
@@ -24,18 +24,19 @@
 
 	[connection executeCommand: @"DROP TABLE IF EXISTS test"];
 	[connection executeCommand: @"CREATE TABLE test ("
 				    @"    id integer,"
 				    @"    name varchar(255),"
-				    @"    content text"
+				    @"    content text,"
+				    @"    success boolean"
 				    @")"];
 	[connection executeCommand: @"INSERT INTO test (id, name, content) "
-				    @"VALUES($1, $2, $3)"
-			parameters: @"1", @"foo", @"Hallo Welt!", nil];
-	[connection executeCommand: @"INSERT INTO test (id, content) "
-				    @"VALUES($1, $2)"
-			parameters: @"2", @"Blup!!", nil];
+				    @"VALUES ($1, $2, $3)"
+			parameters: @1, @"foo", @"Hallo Welt!", nil];
+	[connection executeCommand: @"INSERT INTO test (id, content, success) "
+				    @"VALUES ($1, $2, $3)"
+			parameters: @2, @2, @YES];
 	[connection insertRow: @{ @"content": @"Hallo!", @"name": @"foo" }
 		    intoTable: @"test"];
 
 	result = [connection executeCommand: @"SELECT * FROM test"];
 	of_log(@"%@", result);