diff --git a/index/as/asis.toml b/index/as/asis.toml
index 4611bb72..f5aed58a 100644
--- a/index/as/asis.toml
+++ b/index/as/asis.toml
@@ -5,6 +5,11 @@ authors = ["AdaCore"]
 website = "https://www.adacore.com/download/more"
 maintainers = ["alejandro@mosteo.com"]
 maintainers-logins = ["mosteo"]
+project-files = ["asis.gpr"]
+
+    [[general.actions]]
+    type = "post-fetch"
+    command = ["make", "setup-snames"]
 
     [general.depends-on]
     make = "any"
@@ -13,26 +18,14 @@ maintainers-logins = ["mosteo"]
 origin = "http://mirrors.cdn.adacore.com/art/5b0819e0c7a447df26c27ab8"
 archive-name = "asis-gpl-2018-20180524-src.tar.gz"
 origin-hashes= ["sha512:e00750adf17df8d534f0e561d129002d8b3c9efd6ba9c8d6768840d1399933271d748bafb7358a45d0a520620a335e669a6c2770ed89660bb319b609961a433a"]
-project-files = ["asis.gpr"]
 
-    [[2018.actions]]
-    type = "post-fetch"
-    command = ["make", "setup-snames"]
-
-    [2018.available.'case(compiler)']
-    gnat-community-2018 = true
-    "..." = false
+    [2018.depends-on]
+    gnat = "^2018"
 
 [2017]
 origin = "http://mirrors.cdn.adacore.com/art/591c45e2c7a447af2deecffb"
 archive-name = "asis-gpl-2017-src.tar.gz"
 origin-hashes = ["sha512:dee6b8e0851a4b3181d50256697865f7a6a613eef7b59e43cb1a0b066e794d927db9f60df33f7e1af343d41801a6b66feb1f7a963523b2442c85ca506d7e112f"]
-project-files = ["asis.gpr"]
 
-    [[2017.actions]]
-    type = "post-fetch"
-    command = ["make", "setup-snames"]
-
-    [2017.available.'case(compiler)']
-    gnat-community-2018 = true
-    "..." = false
+    [2017.depends-on]
+    gnat = "^2017"
diff --git a/index/gn/gnatcoll.toml b/index/gn/gnatcoll.toml
index e76e091f..1c97422f 100644
--- a/index/gn/gnatcoll.toml
+++ b/index/gn/gnatcoll.toml
@@ -6,7 +6,7 @@ maintainers = ["derodat@adacore.com"]
 maintainers-logins = ["pmderodat"]
 
 # This crate has a hidden conflict with any other gnatcoll.
-# Declaring conflicts was removed during index transition 
+# Declaring conflicts was removed during index transition
 # and it's still not reinstated.
 
     [general.gpr-externals]
@@ -33,9 +33,8 @@ origin-hashes = ["""\
 """]
 project-files = ["gnatcoll-core-gpl-2018-src/gnatcoll.gpr"]
 
-    [2018.available.'case(compiler)']
-    'gnat-community-2018' = true
-    '...' = false
+    [2018.depends-on]
+    gnat = "^2018"
 
 [2019]
 origin = """https://community.download.adacore.com/v1/\
@@ -47,9 +46,5 @@ origin-hashes = ["""\
 """]
 project-files = ["gnatcoll.gpr"]
 
-    [2019.available.'case(compiler)']
-    'gnat-fsf-9-0' = true
-    'gnat-fsf-9-1' = true
-    'gnat-fsf-9-2-or-newer' = true
-    'gnat-community-2019' = true
-    '...' = false
+    [2019.depends-on]
+    gnat = "^2019 | (>=9.0 & <2000)"
diff --git a/index/gn/gnatcoll_gmp.toml b/index/gn/gnatcoll_gmp.toml
index e4c0c690..151b5101 100644
--- a/index/gn/gnatcoll_gmp.toml
+++ b/index/gn/gnatcoll_gmp.toml
@@ -25,14 +25,8 @@ origin-hashes = ["""\
     a6d2234a6dd64c5acd4b1bafffa7ce7f1080bd51fbb8bc88edfcc855b7a48\
 """]
 
-    [2019.available.'case(compiler)']
-    'gnat-fsf-9-0' = true
-    'gnat-fsf-9-1' = true
-    'gnat-fsf-9-2-or-newer' = true
-    'gnat-community-2019' = true
-    '...' = false
-
     [2019.depends-on]
+    gnat = ">=9.0"
     gnatcoll = "^2019"
     libgmp = "^6.1"
 
diff --git a/index/gn/gnatcoll_iconv.toml b/index/gn/gnatcoll_iconv.toml
index 5750a7c5..69d8e0a3 100644
--- a/index/gn/gnatcoll_iconv.toml
+++ b/index/gn/gnatcoll_iconv.toml
@@ -33,14 +33,8 @@ origin-hashes = ["""\
     a6d2234a6dd64c5acd4b1bafffa7ce7f1080bd51fbb8bc88edfcc855b7a48\
 """]
 
-    [2019.available.'case(compiler)']
-    'gnat-fsf-9-0' = true
-    'gnat-fsf-9-1' = true
-    'gnat-fsf-9-2-or-newer' = true
-    'gnat-community-2019' = true
-    '...' = false
-
     [2019.depends-on]
+    gnat = ">=9.0"
     gnatcoll = "^2019"
 
     [2019.gpr-set-externals]