diff --git a/base/mf_isint.sas b/base/mf_isint.sas
index 0cb7f87..71548bb 100644
--- a/base/mf_isint.sas
+++ b/base/mf_isint.sas
@@ -20,8 +20,11 @@
 
 %macro mf_isint(arg
 )/*/STORE SOURCE*/;
-  /* remove minus sign if exists */
 
+  /* blank val is not an integer */
+  %if "&arg"="" %then %do;0%return;%end;
+
+  /* remove minus sign if exists */
   %local val;
   %if "%substr(%str(&arg),1,1)"="-" %then %let val=%substr(%str(&arg),2);
   %else %let val=&arg;
diff --git a/tests/crossplatform/mf_isint.test.sas b/tests/crossplatform/mf_isint.test.sas
index 7d2bfae..9759649 100644
--- a/tests/crossplatform/mf_isint.test.sas
+++ b/tests/crossplatform/mf_isint.test.sas
@@ -30,4 +30,12 @@
   ),
   desc=Checking mf_isint(-1),
   outds=work.test_results
+)
+
+%mp_assert(
+  iftrue=(
+    "%mf_isint()"="0"
+  ),
+  desc=Checking mf_isint(),
+  outds=work.test_results
 )
\ No newline at end of file