diff --git a/src/ca/access.cpp b/src/ca/access.cpp
index 433e227d2..a9bca73df 100644
--- a/src/ca/access.cpp
+++ b/src/ca/access.cpp
@@ -631,9 +631,9 @@ extern "C" int epicsShareAPI ca_pend_event (ca_real timeout)
         return status;
     }
 
+    // preserve past odd ball behavior of waiting forever when
+    // the delay is zero
     if ( timeout == 0.0 ) {
-        // preserve past odd ball behavior of waiting forever when
-        // the delay is zero
         while ( true ) {
             pcac->pendEvent ( 60.0 );
         }
@@ -653,6 +653,12 @@ extern "C" int epicsShareAPI ca_pend_io (ca_real timeout)
         return status;
     }
 
+    // preserve past odd ball behavior of waiting forever when
+    // the delay is zero
+    if ( timeout == 0.0 ) {
+        return pcac->pendIO ( DBL_MAX );
+    }
+
     return pcac->pendIO ( timeout );
 }