diff --git a/config/config.go b/config/config.go
index f77ca475c..62f265844 100644
--- a/config/config.go
+++ b/config/config.go
@@ -814,6 +814,52 @@ func (c *Config) Validate() tfdiags.Diagnostics {
 				}
 			}
 
+			// Detect a common mistake of using a "count"ed resource in
+			// an output value without using the splat or index form.
+			// Prior to 0.11 this error was silently ignored, but outputs
+			// now have their errors checked like all other contexts.
+			//
+			// TODO: Remove this in 0.12.
+			for _, v := range o.RawConfig.Variables {
+				rv, ok := v.(*ResourceVariable)
+				if !ok {
+					continue
+				}
+
+				// If the variable seems to be treating the referenced
+				// resource as a singleton (no count specified) then
+				// we'll check to make sure it is indeed a singleton.
+				// It's a warning if not.
+
+				if rv.Multi || rv.Index != 0 {
+					// This reference is treating the resource as a
+					// multi-resource, so the warning doesn't apply.
+					continue
+				}
+
+				for _, r := range c.Resources {
+					if r.Id() != rv.ResourceId() {
+						continue
+					}
+
+					// We test specifically for the raw string "1" here
+					// because we _do_ want to generate this warning if
+					// the user has provided an expression that happens
+					// to return 1 right now, to catch situations where
+					// a count might dynamically be set to something
+					// other than 1 and thus splat syntax is still needed
+					// to be safe.
+					if r.RawCount != nil && r.RawCount.Raw != nil && r.RawCount.Raw["count"] != "1" {
+						diags = diags.Append(tfdiags.SimpleWarning(fmt.Sprintf(
+							"output %q: must use splat syntax to access %s attribute %q, because it has \"count\" set; use %s.*.%s to obtain a list of the attributes across all instances",
+							o.Name,
+							r.Id(), rv.Field,
+							r.Id(), rv.Field,
+						)))
+					}
+				}
+			}
+
 		}
 	}