diff --git a/libs/3rd-party/locsat/data/iasp91.P b/libs/3rd-party/locsat/data/iasp91.P
index 321054a47..db3614bfa 100644
--- a/libs/3rd-party/locsat/data/iasp91.P
+++ b/libs/3rd-party/locsat/data/iasp91.P
@@ -23,7 +23,7 @@ n # P1      travel-time (and amplitude) tables
   170.00  171.00  172.00  173.00  174.00  175.00  176.00  177.00  178.00  179.00
   180.00
 # Travel-time/amplitude for z =    0.00
-       0.147
+       0.000
       19.170
       34.925
       48.677
diff --git a/libs/3rd-party/locsat/data/iasp91.S b/libs/3rd-party/locsat/data/iasp91.S
index b8650fef8..5f36aa740 100644
--- a/libs/3rd-party/locsat/data/iasp91.S
+++ b/libs/3rd-party/locsat/data/iasp91.S
@@ -16,7 +16,7 @@ n # S      travel-time (and amplitude) tables
   100.00  101.00  102.00  103.00  104.00  105.00  106.00  107.00  108.00  109.00
   110.00  111.00  112.00  113.00  114.00  115.00  116.00  117.00
 # Travel-time/amplitude for z =    0.00
-      -0.716
+       0.000
       32.367
       61.176
       85.909