diff --git a/Makefile b/Makefile
index a86c213..63beed8 100644
--- a/Makefile
+++ b/Makefile
@@ -34,6 +34,7 @@ all:
 		${LIBS}			\
 		${SRCS}
 
+.PHONY: test
 test:
 	@objfw-compile			\
 		-o test			\
diff --git a/PGConnection.m b/PGConnection.m
index 82177ac..d2cb292 100644
--- a/PGConnection.m
+++ b/PGConnection.m
@@ -99,7 +99,20 @@
 		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);
 
diff --git a/PGResultRow.m b/PGResultRow.m
index 94d9b84..880595c 100644
--- a/PGResultRow.m
+++ b/PGResultRow.m
@@ -1,5 +1,25 @@
 #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;
@@ -67,7 +87,8 @@
 	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
@@ -133,6 +154,7 @@
 	if (pos >= count)
 		return nil;
 
-	return [OFString stringWithUTF8String: PQgetvalue(res, row, pos++)];
+	return convert_type(res, pos,
+	    [OFString stringWithUTF8String: PQgetvalue(res, row, pos++)]);
 }
 @end
diff --git a/test.m b/test.m
index 4b77047..a3e354d 100644
--- a/test.m
+++ b/test.m
@@ -26,14 +26,15 @@ OF_APPLICATION_DELEGATE(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"];