diff --git a/src/alire/alire.adb b/src/alire/alire.adb
index 88857118b..6a0c23b6e 100644
--- a/src/alire/alire.adb
+++ b/src/alire/alire.adb
@@ -11,6 +11,8 @@ with GNATCOLL.OS.Constants;
 
 package body Alire is
 
+   package OS renames GNAT.OS_Lib;
+
    ---------
    -- "=" --
    ---------
@@ -37,7 +39,17 @@ package body Alire is
    -- Check_Absolute_Path --
    -------------------------
 
-   function Check_Absolute_Path (Path : Any_Path) return Boolean is separate;
+   function Check_Absolute_Path (Path : Any_Path) return Boolean
+      is (OS.Is_Absolute_Path (Path)
+          and then
+          --  On Windows, we must ensure the path is not only absolute but
+          --  also that it has a drive letter. This is not checked by the
+          --  GNAT.OS_Lib function.
+            (if OS.Directory_Separator = '\'
+             then
+               (Path'Length >= 3
+                and then Path (Path'First) in 'a' .. 'z' | 'A' .. 'Z'
+                and then Path (Path'First + 1) = ':')));
 
    -------------
    -- Err_Log --
diff --git a/src/alire/os_freebsd/alire-check_absolute_path.adb b/src/alire/os_freebsd/alire-check_absolute_path.adb
deleted file mode 100644
index 01caa2a3d..000000000
--- a/src/alire/os_freebsd/alire-check_absolute_path.adb
+++ /dev/null
@@ -1,7 +0,0 @@
-separate (Alire)
-function Check_Absolute_Path (Path : Any_Path) return Boolean is
-begin
-   return (Path'Length >= 1
-            and then
-           Path (Path'First) = GNAT.OS_Lib.Directory_Separator);
-end Check_Absolute_Path;
diff --git a/src/alire/os_linux/alire-check_absolute_path.adb b/src/alire/os_linux/alire-check_absolute_path.adb
deleted file mode 100644
index 01caa2a3d..000000000
--- a/src/alire/os_linux/alire-check_absolute_path.adb
+++ /dev/null
@@ -1,7 +0,0 @@
-separate (Alire)
-function Check_Absolute_Path (Path : Any_Path) return Boolean is
-begin
-   return (Path'Length >= 1
-            and then
-           Path (Path'First) = GNAT.OS_Lib.Directory_Separator);
-end Check_Absolute_Path;
diff --git a/src/alire/os_macos/alire-check_absolute_path.adb b/src/alire/os_macos/alire-check_absolute_path.adb
deleted file mode 100644
index 01caa2a3d..000000000
--- a/src/alire/os_macos/alire-check_absolute_path.adb
+++ /dev/null
@@ -1,7 +0,0 @@
-separate (Alire)
-function Check_Absolute_Path (Path : Any_Path) return Boolean is
-begin
-   return (Path'Length >= 1
-            and then
-           Path (Path'First) = GNAT.OS_Lib.Directory_Separator);
-end Check_Absolute_Path;
diff --git a/src/alire/os_openbsd/alire-check_absolute_path.adb b/src/alire/os_openbsd/alire-check_absolute_path.adb
deleted file mode 100644
index 01caa2a3d..000000000
--- a/src/alire/os_openbsd/alire-check_absolute_path.adb
+++ /dev/null
@@ -1,7 +0,0 @@
-separate (Alire)
-function Check_Absolute_Path (Path : Any_Path) return Boolean is
-begin
-   return (Path'Length >= 1
-            and then
-           Path (Path'First) = GNAT.OS_Lib.Directory_Separator);
-end Check_Absolute_Path;
diff --git a/src/alire/os_windows/alire-check_absolute_path.adb b/src/alire/os_windows/alire-check_absolute_path.adb
deleted file mode 100644
index fb3f170d2..000000000
--- a/src/alire/os_windows/alire-check_absolute_path.adb
+++ /dev/null
@@ -1,10 +0,0 @@
-separate (Alire)
-function Check_Absolute_Path (Path : Any_Path) return Boolean is
-begin
-   return (Path'Length >= 3
-           and then Path (Path'First) in 'A' .. 'Z' | 'a' .. 'z'
-           and then Path (Path'First + 1) = ':'
-           and then Path (Path'First + 2) in '\' | '/');
-   --  Even strictly speaking, smthg like C:/ can only be an absolute path that
-   --  comes from some non-Windows native program (git from msys2 or the like).
-end Check_Absolute_Path;
diff --git a/testsuite/run.sh b/testsuite/run.sh
new file mode 100755
index 000000000..4a2162365
--- /dev/null
+++ b/testsuite/run.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+clear
+python3 run.py -M1 "$@"