diff --git a/sqlsrv/schema.inc b/sqlsrv/schema.inc
index 9be2af8..82b4f32 100755
--- a/sqlsrv/schema.inc
+++ b/sqlsrv/schema.inc
@@ -676,7 +676,7 @@ EOF
       $sql .= ' COLLATE ' . $spec['sqlsrv_collation'];
     }
 
-    if (isset($spec['not null']) && $spec['not null']) {
+    if (isset($spec['not null']) && $spec['not null']==TRUE) {
       $sql .= ' NOT NULL';
     }
 
@@ -1001,7 +1001,7 @@ EOF
     // If the field is declared NOT NULL, we have to first create it NULL insert
     // the initial data (or populate default values) and then switch to NOT NULL.
     $fixnull = FALSE;
-    if (!empty($spec['not null'])) {
+    if (isset($spec['not null']) && $spec['not null']==TRUE) {
       $fixnull = TRUE;
       $spec['not null'] = FALSE;
     }
@@ -1134,7 +1134,7 @@ EOF
     // create it first as nullable, then either migrate
     // data from previous column or populate default values.
     $fixnull = FALSE;
-    if (!empty($spec['not null'])) {
+    if (isset($spec['not null']) && $spec['not null']==TRUE) {
       $fixnull = TRUE;
       $spec['not null'] = FALSE;
     }