diff --git a/CHANGES b/CHANGES
index 9adb69d5e4..cdd2709cf1 100644
--- a/CHANGES
+++ b/CHANGES
@@ -11,6 +11,10 @@
          *) applies to 0.9.6a (/0.9.6b) and 0.9.7
          +) applies to 0.9.7 only
 
+  *) When only the key is given to "enc", the IV is undefined. Print out
+     an error message in this case.
+     [Lutz Jaenicke]
+
   +) Added the OS2-EMX target.
      ["Brian Havard" <brianh@kheldar.apana.org.au> and Richard Levitte]
 
diff --git a/apps/enc.c b/apps/enc.c
index 49cae7579c..3c72d05c6c 100644
--- a/apps/enc.c
+++ b/apps/enc.c
@@ -488,6 +488,14 @@ bad:
 			BIO_printf(bio_err,"invalid hex iv value\n");
 			goto end;
 			}
+		if ((hiv == NULL) && (str == NULL))
+			{
+			/* No IV was explicitly set and no IV was generated
+			 * during EVP_BytesToKey. Hence the IV is undefined,
+			 * making correct decryption impossible. */
+			BIO_printf(bio_err, "iv undefined\n");
+			goto end;
+			}
 		if ((hkey != NULL) && !set_hex(hkey,key,sizeof key))
 			{
 			BIO_printf(bio_err,"invalid hex key value\n");
diff --git a/doc/apps/enc.pod b/doc/apps/enc.pod
index 9323223cd2..99b914789d 100644
--- a/doc/apps/enc.pod
+++ b/doc/apps/enc.pod
@@ -97,12 +97,18 @@ of hex digits.
 =item B<-K key>
 
 the actual key to use: this must be represented as a string comprised only
-of hex digits.
+of hex digits. If only the key is specified, the IV must additionally specified
+using the B<-iv> option. When both a key and a password are specified, the
+key given with the B<-K> option will be used and the IV generated from the
+password will be taken. It probably does not make much sense to specify
+both key and password.
 
 =item B<-iv IV>
 
 the actual IV to use: this must be represented as a string comprised only
-of hex digits.
+of hex digits. When only the key is specified using the B<-K> option, the
+IV must explicitly be defined. When a password is being specified using
+one of the other options, the IV is generated from this password.
 
 =item B<-p>