diff --git a/src/java/log4j.properties b/src/java/log4j.properties
index a912f3a3c..1eef6c248 100644
--- a/src/java/log4j.properties
+++ b/src/java/log4j.properties
@@ -6,26 +6,26 @@ log4j.category.org.apache.poi.poifs=debug,  poifsLog
 log4j.category.org.apache.poi.util=debug,  utilLog
 
 log4j.appender.hssfLog=org.apache.log4j.FileAppender
-log4j.appender.hssfLog.File=hssf.log
+log4j.appender.hssfLog.File=build/hssf.log
 log4j.appender.hssfLog.layout=org.apache.log4j.PatternLayout
 log4j.appender.hssfLog.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
 
 log4j.appender.hdfLog=org.apache.log4j.FileAppender
-log4j.appender.hdfLog.File=hdf.log
+log4j.appender.hdfLog.File=build/hdf.log
 log4j.appender.hdfLog.layout=org.apache.log4j.PatternLayout
 log4j.appender.hdfLog.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
 
 log4j.appender.hpsfLog=org.apache.log4j.FileAppender
-log4j.appender.hpsfLog.File=hpsf.log
+log4j.appender.hpsfLog.File=build/hpsf.log
 log4j.appender.hpsfLog.layout=org.apache.log4j.PatternLayout
 log4j.appender.hpsfLog.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
 
 log4j.appender.poifsLog=org.apache.log4j.FileAppender
-log4j.appender.poifsLog.File=poifs.log
+log4j.appender.poifsLog.File=build/poifs.log
 log4j.appender.poifsLog.layout=org.apache.log4j.PatternLayout
 log4j.appender.poifsLog.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n
 
 log4j.appender.utilLog=org.apache.log4j.FileAppender
-log4j.appender.utilLog.File=util.log
+log4j.appender.utilLog.File=build/util.log
 log4j.appender.utilLog.layout=org.apache.log4j.PatternLayout
 log4j.appender.utilLog.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n