diff --git a/VMTests.md b/VMTests.md
index d8ac14420..0163d08cb 100644
--- a/VMTests.md
+++ b/VMTests.md
@@ -406,8 +406,8 @@ OK: 33/52 Fail: 4/52 Skip: 15/52
 + deadCode_1.json                                                 OK
 + dupAt51becameMload.json                                         OK
 - extcodecopyMemExp.json                                          Fail
-- for_loop1.json                                                  Fail
-- for_loop2.json                                                  Fail
++ for_loop1.json                                                  OK
++ for_loop2.json                                                  OK
 + gas0.json                                                       OK
 + gas1.json                                                       OK
 + gasOverFlow.json                                                OK
@@ -451,7 +451,7 @@ OK: 33/52 Fail: 4/52 Skip: 15/52
 + loop_stacklimit_1021.json                                       OK
 + memory1.json                                                    OK
 + mloadError0.json                                                OK
-- mloadError1.json                                                Fail
++ mloadError1.json                                                OK
 + mloadMemExp.json                                                OK
 + mloadOutOfGasError2.json                                        OK
 + msize0.json                                                     OK
@@ -472,7 +472,7 @@ OK: 33/52 Fail: 4/52 Skip: 15/52
 + pop0.json                                                       OK
 + pop1.json                                                       OK
 + return1.json                                                    OK
-- return2.json                                                    Fail
++ return2.json                                                    OK
 + sha3MemExp.json                                                 OK
 + sstore_load_0.json                                              OK
 + sstore_load_1.json                                              OK
@@ -483,7 +483,7 @@ OK: 33/52 Fail: 4/52 Skip: 15/52
 + swapAt52becameMstore.json                                       OK
 + when.json                                                       OK
 ```
-OK: 134/145 Fail: 10/145 Skip: 1/145
+OK: 138/145 Fail: 6/145 Skip: 1/145
 ## vmLogTest
 ```diff
 + log0_emptyMem.json                                              OK
diff --git a/nimbus/vm/interpreter/gas_costs.nim b/nimbus/vm/interpreter/gas_costs.nim
index b127cb197..0da68e824 100644
--- a/nimbus/vm/interpreter/gas_costs.nim
+++ b/nimbus/vm/interpreter/gas_costs.nim
@@ -124,24 +124,29 @@ template gasCosts(FeeSchedule: GasFeeSchedule, prefix, ResultGasCostsName: untyp
     #   Except when memLength = 0, where per eq (297),
     #   M(currentMemSize, f, l) = currentMemSize
 
-    if memLength == 0:
+    let
+      prev_words = currentMemSize.wordCount
+      new_words = (memOffset + memLength).wordCount
+
+    if memLength == 0 or new_words <= prev_words:
       # Special subcase of memory-expansion cost
       # currentMemSize - currentMemSize = 0
       # "Referencing a zero length range ... does not require memory to be extended
       #  to the beginning of the range."
+      #
+      # Also, don't credit EVM code for allocating memory
+      # then accessing lots of low memory. memoryGasCost,
+      # via go-ethereum, checks for this as special case.
       return 0
 
     let
-      prev_words = currentMemSize.wordCount
       prev_cost = prev_words * static(FeeSchedule[GasMemory]) +
         (prev_words ^ 2) shr 9 # div 512
-
-      new_words = (memOffset + memLength).wordCount
       new_cost = new_words * static(FeeSchedule[GasMemory]) +
         (new_words ^ 2) shr 9 # div 512
 
     # TODO: add logging
-    result = new_cost - prev_cost
+    result = max(new_cost - prev_cost, 0)
 
   func `prefix all_but_one_64th`(gas: GasInt): GasInt {.inline.} =
     ## Computes all but 1/64th