diff --git a/vhdlpp/subprogram.cc b/vhdlpp/subprogram.cc
index bfa1be9a7..a6bd8f63f 100644
--- a/vhdlpp/subprogram.cc
+++ b/vhdlpp/subprogram.cc
@@ -268,8 +268,14 @@ bool Subprogram::fixed_return_type(void)
         (*s)->visit(r);
     }
 
-    const VType*return_type = r.get_type();
+    VType*return_type = const_cast<VType*>(r.get_type());
     if(return_type && !return_type->is_unbounded()) {
+        // Let's check if the variable length can be evaluated without any scope.
+        // If not, then it is depends on information about e.g. function params
+        if(return_type->is_variable_length(NULL)) {
+            if(VTypeArray*arr = dynamic_cast<VTypeArray*>(return_type))
+                arr->evaluate_ranges(this);
+        }
         return_type_ = return_type;
         return true;
     } else {
diff --git a/vhdlpp/vtype.cc b/vhdlpp/vtype.cc
index cd4ea42e1..3f2368b5f 100644
--- a/vhdlpp/vtype.cc
+++ b/vhdlpp/vtype.cc
@@ -186,6 +186,19 @@ bool VTypeArray::is_variable_length(ScopeBase*scope) const {
     return etype_->is_variable_length(scope);
 }
 
+void VTypeArray::evaluate_ranges(ScopeBase*scope) {
+    for(std::vector<range_t>::iterator it = ranges_.begin(); it != ranges_.end(); ++it ) {
+        int64_t lsb_val = -1, msb_val = -1;
+        bool dir = it->is_downto();
+
+        if(it->msb()->evaluate(scope, msb_val) && it->lsb()->evaluate(scope, lsb_val)) {
+            assert(lsb_val >= 0);
+            assert(msb_val >= 0);
+            *it = range_t(new ExpInteger(msb_val), new ExpInteger(lsb_val), dir);
+        }
+    }
+}
+
 VTypeRange::VTypeRange(const VType*base, int64_t max_val, int64_t min_val)
 : base_(base)
 {
diff --git a/vhdlpp/vtype.h b/vhdlpp/vtype.h
index b417cbafb..0e602d5ec 100644
--- a/vhdlpp/vtype.h
+++ b/vhdlpp/vtype.h
@@ -238,6 +238,10 @@ class VTypeArray : public VType {
 	// To handle subtypes
       inline void set_parent_type(const VTypeArray*parent) { parent_ = parent; }
 
+	// Wherever it is possible, replaces range lsb & msb expressions with
+	// constant integers.
+      void evaluate_ranges(ScopeBase*scope);
+
     private:
       int emit_with_dims_(std::ostream&out, bool packed, perm_string name) const;