diff --git a/harbour/source/common/hbstr.c b/harbour/source/common/hbstr.c
index 5bbbc3ac73..66af96670a 100644
--- a/harbour/source/common/hbstr.c
+++ b/harbour/source/common/hbstr.c
@@ -337,7 +337,7 @@ static double hb_numPow10( int nPrecision )
       }
       else if( nPrecision > -16 )
       {
-         return 1.0 / s_dPow10[ ( unsigned int ) nPrecision ];
+         return 1.0 / s_dPow10[ ( unsigned int ) -nPrecision ];
       }
    }