diff --git a/nvm.sh b/nvm.sh
index 4d6bbca..421984e 100644
--- a/nvm.sh
+++ b/nvm.sh
@@ -19,8 +19,12 @@ fi
 
 # Auto detect the NVM_DIR
 if [ ! -d "$NVM_DIR" ]; then
-  if [ -n "$BASH_SOURCE" ]; then
-    export NVM_DIR=$(cd $NVM_CD_FLAGS $(dirname ${BASH_SOURCE[0]:-$0}) > /dev/null && pwd)
+  if [ -n "${BASH_SOURCE}" ]; then
+    export NVM_DIR=$(cd $NVM_CD_FLAGS $(dirname $BASH_SOURCE) > /dev/null && pwd)
+  elif [ "$(basename $0)" = nvm.sh ]; then
+    # Works in shells that put the path of the sourcee into $0. Unfortunately
+    # dash is not among these.
+    export NVM_DIR=$(cd $NVM_CD_FLAGS $(dirname $0) > /dev/null && pwd)
   else
     export NVM_DIR=$HOME/.nvm
   fi
diff --git a/test/fast/$BASH_SOURCE should not be a problem in sh and zsh b/test/fast/$BASH_SOURCE should not be a problem in sh and zsh
new file mode 100755
index 0000000..24a7a18
--- /dev/null
+++ b/test/fast/$BASH_SOURCE should not be a problem in sh and zsh	
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+echo Testing bash
+bash -c '. ../../nvm.sh'
+echo Testing zsh
+zsh -c '. ../../nvm.sh'
+echo Testing sh
+sh -c '. ../../nvm.sh'