diff --git a/README.md b/README.md
index 92c09d0..fc17fa3 100644
--- a/README.md
+++ b/README.md
@@ -155,7 +155,7 @@ The SAS type (char/numeric) of the values is determined according to a set of ru
 
 * If the values are numeric, the SAS type is numeric
 * If the values are all string, the SAS type is character
-* If the values contain a single character (a-Z + underscore) AND a numeric, then the SAS type is numeric (with special missing values).  
+* If the values contain a single character (a-Z + underscore + .) AND a numeric, then the SAS type is numeric (with special missing values).  
 * `null` is set to either '.' or '' depending on the assigned or derived type per the above rules.  If entire column is `null` then the type will be numeric.
 
 The following table illustrates the formats applied to columns under various scenarios:
diff --git a/src/test/utils/formatDataForRequest.spec.ts b/src/test/utils/formatDataForRequest.spec.ts
index eee87a4..4527de9 100644
--- a/src/test/utils/formatDataForRequest.spec.ts
+++ b/src/test/utils/formatDataForRequest.spec.ts
@@ -54,6 +54,17 @@ describe('formatDataForRequest', () => {
     expect(formatDataForRequest(data)).toEqual(expectedOutput)
   })
 
+  it('should accept . as special missing value', () => {
+    let tableWithMissingValues = {
+      [testTable]: [{ var: '.' }, { var: 0 }],
+      [`$${testTable}`]: { formats: { var: 'best.' } }
+    }
+
+    expect(() =>
+      formatDataForRequest(tableWithMissingValues)
+    ).not.toThrowError()
+  })
+
   it('should throw an error if special missing values is not valid', () => {
     let tableWithMissingValues = {
       [testTable]: [{ var: 'AA' }, { var: 0 }],