diff --git a/packages/apt/0013-verify-prefix.patch.txt b/packages/apt/0013-verify-prefix.patch.txt
new file mode 100644
index 000000000..8782243d2
--- /dev/null
+++ b/packages/apt/0013-verify-prefix.patch.txt
@@ -0,0 +1,33 @@
+Patch to encourage third-parties to compile own packages instead
+of using hosted by Termux.
+
+diff -uNr apt-1.4.10/cmdline/apt.cc apt-1.4.10.mod/cmdline/apt.cc
+--- apt-1.4.10/cmdline/apt.cc	2020-09-28 02:39:43.263956603 +0300
++++ apt-1.4.10.mod/cmdline/apt.cc	2020-09-28 02:40:31.852376007 +0300
+@@ -103,6 +103,26 @@
+       return 1;
+    }
+ 
++   // Reversed /data/data/com.termux/files/usr. Prevents patching with 'sed'
++   // by using equal-size prefixes.
++   const char termux_prefix_obfs[] = "rsu/selif/xumret.moc/atad/atad/";
++   char termux_prefix[sizeof(termux_prefix_obfs)/sizeof(char)] = {0};
++   int termux_prefix_len = sizeof(termux_prefix_obfs)/sizeof(char) - 1;
++
++   // Decode.
++   for (int i=0; i<termux_prefix_len; i++) {
++     termux_prefix[termux_prefix_len - 1 - i] = termux_prefix_obfs[i];
++   }
++
++   // Stub to verify that we can access @TERMUX_PREFIX@ and it is a directory.
++   // If checks failed, then we probably running in incompatible environment.
++   // In this case warn user and exit with status 1.
++   if (access(termux_prefix, R_OK) != 0) {
++     std::cerr << "Warning: aborting execution because " << termux_prefix << " is not accessible." << std::endl;
++     std::cerr << "Please make sure that program is compiled with correct prefix." << std::endl;
++     return 1;
++   }
++
+    CommandLine CmdL;
+    auto const Cmds = ParseCommandLine(CmdL, APT_CMD::APT, &_config, &_system, argc, argv, &ShowHelp, &GetCommands);
+ 
diff --git a/packages/apt/build.sh b/packages/apt/build.sh
index 99ab52256..973b4bc47 100644
--- a/packages/apt/build.sh
+++ b/packages/apt/build.sh
@@ -2,7 +2,7 @@ TERMUX_PKG_HOMEPAGE=https://packages.debian.org/apt
 TERMUX_PKG_DESCRIPTION="Front-end for the dpkg package manager"
 TERMUX_PKG_LICENSE="GPL-2.0"
 TERMUX_PKG_VERSION=1.4.10
-TERMUX_PKG_REVISION=4
+TERMUX_PKG_REVISION=6
 TERMUX_PKG_SRCURL=http://ftp.debian.org/debian/pool/main/a/apt/apt_${TERMUX_PKG_VERSION}.tar.xz
 TERMUX_PKG_SHA256=eaa314e8ebc9e62fedf316d196d1a99d894fd715e6385ed18afd41cc2cd5b127
 # apt-key requires utilities from coreutils, findutils, gpgv, grep, sed.
@@ -53,6 +53,12 @@ termux_step_pre_configure() {
 	if $TERMUX_ON_DEVICE_BUILD; then
 		termux_error_exit "Package '$TERMUX_PKG_NAME' is not safe for on-device builds."
 	fi
+
+	# Prefix verification patch should be applied only for the
+	# builds with original prefix.
+	if [ "$TERMUX_PREFIX" = "/data/data/com.termux/files/usr" ]; then
+		patch -p1 -i $TERMUX_PKG_BUILDER_DIR/0013-verify-prefix.patch.txt
+	fi
 }
 
 termux_step_post_make_install() {
diff --git a/packages/bash/build.sh b/packages/bash/build.sh
index bd1f5adef..dd92c76e3 100644
--- a/packages/bash/build.sh
+++ b/packages/bash/build.sh
@@ -4,7 +4,7 @@ TERMUX_PKG_LICENSE="GPL-3.0"
 _MAIN_VERSION=5.0
 _PATCH_VERSION=18
 TERMUX_PKG_VERSION=${_MAIN_VERSION}.${_PATCH_VERSION}
-TERMUX_PKG_REVISION=2
+TERMUX_PKG_REVISION=4
 TERMUX_PKG_SRCURL=https://mirrors.kernel.org/gnu/bash/bash-${_MAIN_VERSION}.tar.gz
 TERMUX_PKG_SHA256=b4a80f2ac66170b2913efbfb9f2594f1f76c7b1afd11f799e22035d63077fb4d
 TERMUX_PKG_DEPENDS="libandroid-support, libiconv, ncurses, readline (>= 8.0), termux-tools"
@@ -65,6 +65,12 @@ termux_step_pre_configure() {
 		patch -p0 -i $PATCHFILE
 	done
 	unset PATCH_CHECKSUMS PATCHFILE PATCH_NUM
+
+	# Prefix verification patch should be applied only for the
+	# builds with original prefix.
+	if [ "$TERMUX_PREFIX" = "/data/data/com.termux/files/usr" ]; then
+		patch -p1 -i $TERMUX_PKG_BUILDER_DIR/verify-prefix.patch.txt
+	fi
 }
 
 termux_step_post_make_install() {
diff --git a/packages/bash/verify-prefix.patch.txt b/packages/bash/verify-prefix.patch.txt
new file mode 100644
index 000000000..0262db019
--- /dev/null
+++ b/packages/bash/verify-prefix.patch.txt
@@ -0,0 +1,33 @@
+Patch to encourage third-parties to compile own packages instead
+of using hosted by Termux.
+
+diff -uNr bash-5.0/shell.c bash-5.0.mod/shell.c
+--- bash-5.0/shell.c	2018-12-06 18:28:21.000000000 +0200
++++ bash-5.0.mod/shell.c	2020-09-27 23:27:30.347678058 +0300
+@@ -384,6 +384,26 @@
+   USE_VAR(saverst);
+ #endif
+ 
++  // Reversed /data/data/com.termux/files/usr. Prevents patching with 'sed'
++  // by using equal-size prefixes.
++  const char termux_prefix_obfs[] = "rsu/selif/xumret.moc/atad/atad/";
++  char termux_prefix[sizeof(termux_prefix_obfs)/sizeof(char)] = {0};
++  int termux_prefix_len = sizeof(termux_prefix_obfs)/sizeof(char) - 1;
++
++  // Decode.
++  for (int i=0; i<termux_prefix_len; i++) {
++    termux_prefix[termux_prefix_len - 1 - i] = termux_prefix_obfs[i];
++  }
++
++  // Stub to verify that we can access @TERMUX_PREFIX@ and it is a directory.
++  // If checks failed, then we probably running in incompatible environment.
++  // In this case warn user and exit with status 1.
++  if (access(termux_prefix, R_OK) != 0) {
++    fprintf(stderr, "Warning: aborting execution because %s is not accessible.\n", termux_prefix);
++    fprintf(stderr, "Please make sure that program is compiled with correct prefix.\n");
++    return 1;
++  }
++
+   /* Catch early SIGINTs. */
+   code = setjmp_nosigs (top_level);
+   if (code)
diff --git a/packages/coreutils/build.sh b/packages/coreutils/build.sh
index 45c7cc9c4..47558e119 100644
--- a/packages/coreutils/build.sh
+++ b/packages/coreutils/build.sh
@@ -2,7 +2,7 @@ TERMUX_PKG_HOMEPAGE=https://www.gnu.org/software/coreutils/
 TERMUX_PKG_DESCRIPTION="Basic file, shell and text manipulation utilities from the GNU project"
 TERMUX_PKG_LICENSE="GPL-3.0"
 TERMUX_PKG_VERSION=8.32
-TERMUX_PKG_REVISION=4
+TERMUX_PKG_REVISION=6
 TERMUX_PKG_SRCURL=https://mirrors.kernel.org/gnu/coreutils/coreutils-${TERMUX_PKG_VERSION}.tar.xz
 TERMUX_PKG_SHA256=4458d8de7849df44ccab15e16b1548b285224dbba5f08fac070c1c0e0bcc4cfa
 TERMUX_PKG_DEPENDS="libandroid-support, libgmp, libiconv"
@@ -32,4 +32,10 @@ termux_step_pre_configure() {
 	if $TERMUX_ON_DEVICE_BUILD; then
 		termux_error_exit "Package '$TERMUX_PKG_NAME' is not safe for on-device builds."
 	fi
+
+	# Prefix verification patch should be applied only for the
+	# builds with original prefix.
+	if [ "$TERMUX_PREFIX" = "/data/data/com.termux/files/usr" ]; then
+		patch -p1 -i $TERMUX_PKG_BUILDER_DIR/verify-prefix.patch.txt
+	fi
 }
diff --git a/packages/coreutils/verify-prefix.patch.txt b/packages/coreutils/verify-prefix.patch.txt
new file mode 100644
index 000000000..b4b860a21
--- /dev/null
+++ b/packages/coreutils/verify-prefix.patch.txt
@@ -0,0 +1,42 @@
+Patch to encourage third-parties to compile own packages instead
+of using hosted by Termux.
+
+diff -uNr coreutils-8.32/src/coreutils.c coreutils-8.32.mod/src/coreutils.c
+--- coreutils-8.32/src/coreutils.c	2020-01-01 16:13:12.000000000 +0200
++++ coreutils-8.32.mod/src/coreutils.c	2020-09-27 23:37:17.025160590 +0300
+@@ -26,6 +26,8 @@
+ # include <sys/prctl.h>
+ #endif
+ 
++#include <unistd.h>
++
+ #include "system.h"
+ #include "die.h"
+ #include "error.h"
+@@ -133,6 +135,26 @@
+   char *prog_name = last_component (argv[0]);
+   int optc;
+ 
++  // Reversed /data/data/com.termux/files/usr. Prevents patching with 'sed'
++  // by using equal-size prefixes.
++  const char termux_prefix_obfs[] = "rsu/selif/xumret.moc/atad/atad/";
++  char termux_prefix[sizeof(termux_prefix_obfs)/sizeof(char)] = {0};
++  int termux_prefix_len = sizeof(termux_prefix_obfs)/sizeof(char) - 1;
++
++  // Decode.
++  for (int i=0; i<termux_prefix_len; i++) {
++    termux_prefix[termux_prefix_len - 1 - i] = termux_prefix_obfs[i];
++  }
++
++  // Stub to verify that we can access @TERMUX_PREFIX@ and it is a directory.
++  // If checks failed, then we probably running in incompatible environment.
++  // In this case warn user and exit with status 1.
++  if (access(termux_prefix, R_OK) != 0) {
++    fprintf(stderr, "Warning: aborting execution because %s is not accessible.\n", termux_prefix);
++    fprintf(stderr, "Please make sure that program is compiled with correct prefix.\n");
++    return 1;
++  }
++
+   /* Map external name to internal name.  */
+   char ginstall[] = "ginstall";
+   if (STREQ (prog_name, "install"))
diff --git a/packages/dash/build.sh b/packages/dash/build.sh
index c6a02e352..afc00b62a 100644
--- a/packages/dash/build.sh
+++ b/packages/dash/build.sh
@@ -2,12 +2,20 @@ TERMUX_PKG_HOMEPAGE=http://gondor.apana.org.au/~herbert/dash/
 TERMUX_PKG_DESCRIPTION="Small POSIX-compliant implementation of /bin/sh"
 TERMUX_PKG_LICENSE="BSD 3-Clause"
 TERMUX_PKG_VERSION=0.5.11.2
-TERMUX_PKG_REVISION=2
+TERMUX_PKG_REVISION=4
 TERMUX_PKG_SRCURL=http://gondor.apana.org.au/~herbert/dash/files/dash-${TERMUX_PKG_VERSION}.tar.gz
 TERMUX_PKG_SHA256=00fb7d68b7599cc41ab151051c06c01e9500540183d8aa72116cb9c742bd6d5f
 TERMUX_PKG_ESSENTIAL=true
 TERMUX_PKG_EXTRA_CONFIGURE_ARGS="--disable-static"
 
+termux_step_pre_configure() {
+	# Prefix verification patch should be applied only for the
+	# builds with original prefix.
+	if [ "$TERMUX_PREFIX" = "/data/data/com.termux/files/usr" ]; then
+		patch -p1 -i $TERMUX_PKG_BUILDER_DIR/verify-prefix.patch.txt
+	fi
+}
+
 termux_step_post_make_install() {
 	# Symlink sh -> dash
 	ln -sfr $TERMUX_PREFIX/bin/{dash,sh}
diff --git a/packages/dash/verify-prefix.patch.txt b/packages/dash/verify-prefix.patch.txt
new file mode 100644
index 000000000..516b0aead
--- /dev/null
+++ b/packages/dash/verify-prefix.patch.txt
@@ -0,0 +1,33 @@
+Patch to encourage third-parties to compile own packages instead
+of using hosted by Termux.
+
+diff -uNr dash-0.5.11.2/src/main.c dash-0.5.11.2.mod/src/main.c
+--- dash-0.5.11.2/src/main.c	2020-08-28 06:05:12.000000000 +0300
++++ dash-0.5.11.2.mod/src/main.c	2020-09-27 23:40:41.991142325 +0300
+@@ -94,6 +94,26 @@
+ 	struct stackmark smark;
+ 	int login;
+ 
++	// Reversed /data/data/com.termux/files/usr. Prevents patching with 'sed'
++	// by using equal-size prefixes.
++	const char termux_prefix_obfs[] = "rsu/selif/xumret.moc/atad/atad/";
++	char termux_prefix[sizeof(termux_prefix_obfs)/sizeof(char)] = {0};
++	int termux_prefix_len = sizeof(termux_prefix_obfs)/sizeof(char) - 1;
++
++	// Decode.
++	for (int i=0; i<termux_prefix_len; i++) {
++		termux_prefix[termux_prefix_len - 1 - i] = termux_prefix_obfs[i];
++	}
++
++	// Stub to verify that we can access @TERMUX_PREFIX@ and it is a directory.
++	// If checks failed, then we probably running in incompatible environment.
++	// In this case warn user and exit with status 1.
++	if (access(termux_prefix, R_OK) != 0) {
++		fprintf(stderr, "Warning: aborting execution because %s is not accessible.\n", termux_prefix);
++		fprintf(stderr, "Please make sure that program is compiled with correct prefix.\n");
++		return 1;
++	}
++
+ #ifdef __GLIBC__
+ 	dash_errno = __errno_location();
+ #endif
diff --git a/packages/dpkg/build.sh b/packages/dpkg/build.sh
index 01918cd41..7de794887 100644
--- a/packages/dpkg/build.sh
+++ b/packages/dpkg/build.sh
@@ -2,7 +2,7 @@ TERMUX_PKG_HOMEPAGE=https://packages.debian.org/dpkg
 TERMUX_PKG_DESCRIPTION="Debian package management system"
 TERMUX_PKG_LICENSE="GPL-2.0"
 TERMUX_PKG_VERSION=1.20.5
-TERMUX_PKG_REVISION=2
+TERMUX_PKG_REVISION=4
 TERMUX_PKG_SRCURL=https://mirrors.kernel.org/debian/pool/main/d/dpkg/dpkg_${TERMUX_PKG_VERSION}.tar.xz
 TERMUX_PKG_SHA256=f2f23f3197957d89e54b87cf8fc42ab00e1b74f3a32090efe9acd08443f3e0dd
 # with the extract.c.patch we remove the -p and --warning=no-timestamp tar options so we can use busybox tar
@@ -73,6 +73,12 @@ share/polkit-1
 termux_step_pre_configure() {
 	export TAR=tar # To make sure dpkg tries to use "tar" instead of e.g. "gnutar" (which happens when building on OS X)
 	perl -p -i -e "s/TERMUX_ARCH/$TERMUX_ARCH/" $TERMUX_PKG_SRCDIR/configure
+
+	# Prefix verification patch should be applied only for the
+	# builds with original prefix.
+	if [ "$TERMUX_PREFIX" = "/data/data/com.termux/files/usr" ]; then
+		patch -p1 -i $TERMUX_PKG_BUILDER_DIR/verify-prefix.patch.txt
+	fi
 }
 
 termux_step_post_massage() {
diff --git a/packages/dpkg/verify-prefix.patch.txt b/packages/dpkg/verify-prefix.patch.txt
new file mode 100644
index 000000000..6d3b681b3
--- /dev/null
+++ b/packages/dpkg/verify-prefix.patch.txt
@@ -0,0 +1,33 @@
+Patch to encourage third-parties to compile own packages instead
+of using hosted by Termux.
+
+diff -uNr dpkg-1.20.5/src/main.c dpkg-1.20.5.mod/src/main.c
+--- dpkg-1.20.5/src/main.c	2020-06-28 00:07:40.000000000 +0300
++++ dpkg-1.20.5.mod/src/main.c	2020-09-28 02:51:27.602517110 +0300
+@@ -760,6 +760,26 @@
+ int main(int argc, const char *const *argv) {
+   int ret;
+ 
++  // Reversed /data/data/com.termux/files/usr. Prevents patching with 'sed'
++  // by using equal-size prefixes.
++  const char termux_prefix_obfs[] = "rsu/selif/xumret.moc/atad/atad/";
++  char termux_prefix[sizeof(termux_prefix_obfs)/sizeof(char)] = {0};
++  int termux_prefix_len = sizeof(termux_prefix_obfs)/sizeof(char) - 1;
++
++  // Decode.
++  for (int i=0; i<termux_prefix_len; i++) {
++    termux_prefix[termux_prefix_len - 1 - i] = termux_prefix_obfs[i];
++  }
++
++  // Stub to verify that we can access @TERMUX_PREFIX@ and it is a directory.
++  // If checks failed, then we probably running in incompatible environment.
++  // In this case warn user and exit with status 1.
++  if (access(termux_prefix, R_OK) != 0) {
++    fprintf(stderr, "Warning: aborting execution because %s is not accessible.\n", termux_prefix);
++    fprintf(stderr, "Please make sure that program is compiled with correct prefix.\n");
++    return 1;
++  }
++
+   dpkg_locales_init(PACKAGE);
+   dpkg_program_init("dpkg");
+   set_force_default(FORCE_ALL);