diff -uNr calcurse-4.6.0/src/notify.c calcurse-4.6.0.mod/src/notify.c
--- calcurse-4.6.0/src/notify.c	2020-02-04 23:46:34.000000000 +0200
+++ calcurse-4.6.0.mod/src/notify.c	2020-10-01 20:30:58.355227664 +0300
@@ -137,7 +137,7 @@
 	nbar.cmd[BUFSIZ - 1] = '\0';
 
 	if ((nbar.shell = getenv("SHELL")) == NULL)
-		nbar.shell = "/bin/sh";
+		nbar.shell = "@TERMUX_PREFIX@/bin/sh";
 
 	nbar.notify_all = 0;
 
diff -uNr calcurse-4.6.0/src/utils.c calcurse-4.6.0.mod/src/utils.c
--- calcurse-4.6.0/src/utils.c	2020-02-04 23:46:34.000000000 +0200
+++ calcurse-4.6.0.mod/src/utils.c	2020-10-01 20:31:32.951590892 +0300
@@ -767,7 +767,7 @@
 		return P_tmpdir;
 #endif
 	else
-		return "/tmp";
+		return "@TERMUX_PREFIX@/tmp";
 }
 
 /*