diff --git a/all.sas b/all.sas
index 360f97b..c720190 100644
--- a/all.sas
+++ b/all.sas
@@ -133,7 +133,13 @@ options noquotelenmax;
 %macro mf_existfileref(fref
 )/*/STORE SOURCE*/;
 
-  %if %sysfunc(fileref(&fref))=0 %then %do;
+  %local rc;
+  %let rc=%sysfunc(fileref(&fref));
+  %if &rc=0 %then %do;
+    1
+  %end;
+  %else %if &rc<0 %then %do;
+    %put &sysmacroname: Fileref &fref exists but the underlying file does not;
     1
   %end;
   %else %do;
diff --git a/base/mf_existfileref.sas b/base/mf_existfileref.sas
index bbec773..0423696 100644
--- a/base/mf_existfileref.sas
+++ b/base/mf_existfileref.sas
@@ -17,7 +17,13 @@
 %macro mf_existfileref(fref
 )/*/STORE SOURCE*/;
 
-  %if %sysfunc(fileref(&fref))=0 %then %do;
+  %local rc;
+  %let rc=%sysfunc(fileref(&fref));
+  %if &rc=0 %then %do;
+    1
+  %end;
+  %else %if &rc<0 %then %do;
+    %put &sysmacroname: Fileref &fref exists but the underlying file does not;
     1
   %end;
   %else %do;
diff --git a/tests/base/mf_existfileref.test.sas b/tests/base/mf_existfileref.test.sas
new file mode 100644
index 0000000..d5327d4
--- /dev/null
+++ b/tests/base/mf_existfileref.test.sas
@@ -0,0 +1,35 @@
+/**
+  @file
+  @brief Testing mf_existfileref macro
+
+  <h4> SAS Macros </h4>
+  @li mf_existfileref.sas
+  @li mp_assert.sas
+
+**/
+
+filename ref1 temp;
+filename ref2 temp;
+
+data _null_;
+  file ref1;
+  put 'exists';
+run;
+
+%mp_assert(
+  iftrue=(%mf_existfileref(ref1)=1),
+  desc=Checking fileref WITH target file exists,
+  outds=work.test_results
+)
+
+%mp_assert(
+  iftrue=(%mf_existfileref(ref2)=1),
+  desc=Checking fileref WITHOUT target file exists,
+  outds=work.test_results
+)
+
+%mp_assert(
+  iftrue=(%mf_existfileref(ref3)=0),
+  desc=Checking non-existant fref does not exist,
+  outds=work.test_results
+)