diff --git a/include/verilated_imp.h b/include/verilated_imp.h
index 23214bddd..d19d994e5 100644
--- a/include/verilated_imp.h
+++ b/include/verilated_imp.h
@@ -242,7 +242,7 @@ public:  // But only for verilated*.cpp
         s_s.m_fdps.resize(31);
         std::fill(s_s.m_fdps.begin(), s_s.m_fdps.end(), (FILE*)0);
         s_s.m_fdFreeMct.resize(30);
-        std::iota(s_s.m_fdFreeMct.begin(), s_s.m_fdFreeMct.end(), 1);
+        for (int i = 0, id = 1; i < s_s.m_fdFreeMct.size(); i++, id++) { s_s.m_fdFreeMct[i] = id; }
     }
     ~VerilatedImp() {}
 
@@ -472,7 +472,9 @@ public:  // But only for verilated*.cpp
             s_s.m_fdps.resize(start + excess);
             std::fill(s_s.m_fdps.begin() + start, s_s.m_fdps.end(), (FILE*)0);
             s_s.m_fdFree.resize(excess);
-            std::iota(s_s.m_fdFree.begin(), s_s.m_fdFree.end(), start);
+            for (int i = 0, id = start; i < s_s.m_fdFree.size(); i++, id++) {
+                s_s.m_fdFree[i] = id;
+            }
         }
         IData idx = s_s.m_fdFree.back();
         s_s.m_fdFree.pop_back();