diff --git a/src/steps/generic.rs b/src/steps/generic.rs
index 515ead27..4151057b 100644
--- a/src/steps/generic.rs
+++ b/src/steps/generic.rs
@@ -467,7 +467,10 @@ pub fn run_myrepos_update(base_dirs: &BaseDirs, run_type: RunType) -> Result<()>
 
 pub fn run_custom_command(name: &str, command: &str, ctx: &ExecutionContext) -> Result<()> {
     print_separator(name);
-    ctx.run_type().execute(shell()).arg("-c").arg(command).status_checked()
+    let mut exec = ctx.run_type().execute(shell());
+    #[cfg(unix)]
+    exec.arg("-i");
+    exec.arg("-c").arg(command).status_checked()
 }
 
 pub fn run_composer_update(ctx: &ExecutionContext) -> Result<()> {