diff --git a/terraform/eval_count.go b/terraform/eval_count.go
index 99ddeafee..b09c72e66 100644
--- a/terraform/eval_count.go
+++ b/terraform/eval_count.go
@@ -12,18 +12,13 @@ import (
 )
 
 // evaluateCountExpression is our standard mechanism for interpreting an
-// expression given for a "count" argument on a resource. This should be called
-// from the DynamicExpand of a node representing a resource in order to
-// determine the final count value.
+// expression given for a "count" argument on a resource or a module. This
+// should be called during expansion in order to determine the final count
+// value.
 //
-// If the result is zero or positive and no error diagnostics are returned, then
-// the result is the literal count value to use.
-//
-// If the result is -1, this indicates that the given expression is nil and so
-// the "count" behavior should not be enabled for this resource at all.
-//
-// If error diagnostics are returned then the result is always the meaningless
-// placeholder value -1.
+// evaluateCountExpression differs from evaluateCountExpressionValue by
+// returning an error if the count value is not known, and converting the
+// cty.Value to an integer.
 func evaluateCountExpression(expr hcl.Expression, ctx EvalContext) (int, tfdiags.Diagnostics) {
 	countVal, diags := evaluateCountExpressionValue(expr, ctx)
 	if !countVal.IsKnown() {
diff --git a/terraform/eval_for_each.go b/terraform/eval_for_each.go
index 978e034d9..02ec4815b 100644
--- a/terraform/eval_for_each.go
+++ b/terraform/eval_for_each.go
@@ -8,11 +8,14 @@ import (
 	"github.com/zclconf/go-cty/cty"
 )
 
-// evaluateForEachExpression interprets a "for_each" argument on a resource.
+// evaluateForEachExpression is our standard mechanism for interpreting an
+// expression given for a "for_each" argument on a resource or a module. This
+// should be called during expansion in order to determine the final keys and
+// values.
 //
-// Returns a cty.Value map, and diagnostics if necessary. It will return nil if
-// the expression is nil, and is used to distinguish between an unset for_each and an
-// empty map
+// evaluateForEachExpression differs from evaluateForEachExpressionValue by
+// returning an error if the count value is not known, and converting the
+// cty.Value to a map[string]cty.Value for compatibility with other calls.
 func evaluateForEachExpression(expr hcl.Expression, ctx EvalContext) (forEach map[string]cty.Value, diags tfdiags.Diagnostics) {
 	forEachVal, diags := evaluateForEachExpressionValue(expr, ctx)
 	if !forEachVal.IsKnown() {