diff --git a/src/ctlike/ctlike.par b/src/ctlike/ctlike.par
index bd8b77d..89d205f 100644
--- a/src/ctlike/ctlike.par
+++ b/src/ctlike/ctlike.par
@@ -20,7 +20,7 @@
 infile, f, a, "test/data/crab_events.fits.gz",,,"Event list, counts map or observation definition file"
 stat,   s, h, "POISSON",,,            "Optimization statistics"
 refit,  b, h,        no,,,            "Do refitting?"
-caldb,  s, h,         "",,,           "Calibration database"
+caldb,  s, a,         "",,,           "Calibration database"
 irf,    s, a, "cta_dummy_irf",,,      "Instrument response function"
 srcmdl, f, a, "test/data/crab.xml",,, "Source model"
 outmdl, f, a, "crab_results.xml",,,   "Source model output file"
diff --git a/src/ctmodel/ctmodel.par b/src/ctmodel/ctmodel.par
index a48ba56..8a8a6df 100644
--- a/src/ctmodel/ctmodel.par
+++ b/src/ctmodel/ctmodel.par
@@ -20,7 +20,7 @@
 infile,   f, a, "NONE",,, "Input counts map or observation definition file"
 outfile,  f, a, "modmap.fits",,, "Output counts map or observation definition file"
 prefix,   s, h, "modmap_",,, "Prefix for counts maps in observation definition file"
-caldb,    s, h, "",,, "Calibration database"
+caldb,    s, a, "",,, "Calibration database"
 irf,      s, a, "cta_dummy_irf",,, "Instrument response function"
 srcmdl,   f, a, "test/data/crab.xml",,, "Source model"
 #
diff --git a/src/ctobssim/ctobssim.par b/src/ctobssim/ctobssim.par
index e85581f..7d2d123 100644
--- a/src/ctobssim/ctobssim.par
+++ b/src/ctobssim/ctobssim.par
@@ -23,7 +23,7 @@ prefix, s, h, "sim_events_",,,        "Prefix for event lists in observation def
 #
 # Observation parameters
 #=======================
-caldb, s, a, "test/irf",,,    "Calibration database"
+caldb, s, a, "",,,    "Calibration database"
 irf,   s, a, "cta_dummy_irf",,, "Instrument response function"
 #
 # Simulation parameters