diff --git a/bin/lottie_common.sh b/bin/lottie_common.sh
index 0137c37..a04319a 100644
--- a/bin/lottie_common.sh
+++ b/bin/lottie_common.sh
@@ -1,3 +1,4 @@
+#!/usr/bin/sh
 # this is common source file used by lottie_to_gif.sh, lottie_to_webp.sh
 # required bash variables
 # $HEIGHT
diff --git a/bin/lottie_to_apng.sh b/bin/lottie_to_apng.sh
index d8146ec..9e4634c 100755
--- a/bin/lottie_to_apng.sh
+++ b/bin/lottie_to_apng.sh
@@ -1,3 +1,4 @@
+#!/usr/bin/sh
 HEIGHT=512
 WIDTH=512
 FPS=60
diff --git a/bin/lottie_to_gif.sh b/bin/lottie_to_gif.sh
index db7b469..5a64f57 100755
--- a/bin/lottie_to_gif.sh
+++ b/bin/lottie_to_gif.sh
@@ -1,3 +1,4 @@
+#!/usr/bin/sh
 HEIGHT=512
 WIDTH=512
 FPS=50
diff --git a/bin/lottie_to_png.sh b/bin/lottie_to_png.sh
index 1ca555a..a0d2cac 100755
--- a/bin/lottie_to_png.sh
+++ b/bin/lottie_to_png.sh
@@ -1,3 +1,4 @@
+#!/usr/bin/sh
 HEIGHT=512
 WIDTH=512
 FPS=60
diff --git a/bin/lottie_to_webm.sh b/bin/lottie_to_webm.sh
index 6189a7b..577b2a6 100755
--- a/bin/lottie_to_webm.sh
+++ b/bin/lottie_to_webm.sh
@@ -1,3 +1,4 @@
+#!/usr/bin/sh
 HEIGHT=512
 WIDTH=512
 FPS=60
diff --git a/bin/lottie_to_webp.sh b/bin/lottie_to_webp.sh
index 07df32a..4b79a34 100755
--- a/bin/lottie_to_webp.sh
+++ b/bin/lottie_to_webp.sh
@@ -1,3 +1,4 @@
+#!/usr/bin/sh
 HEIGHT=512
 WIDTH=512
 FPS=60