diff --git a/flang/lib/Semantics/compute-offsets.cpp b/flang/lib/Semantics/compute-offsets.cpp
--- a/flang/lib/Semantics/compute-offsets.cpp
+++ b/flang/lib/Semantics/compute-offsets.cpp
@@ -151,16 +151,12 @@
   for (auto &object : details.objects()) {
     Symbol &symbol{*object};
     DoSymbol(symbol);
+    auto eqIter{equivalenceBlock_.end()};
     auto iter{dependents_.find(symbol)};
     if (iter == dependents_.end()) {
-      // Get full extent of any EQUIVALENCE block into size of COMMON
-      auto eqIter{equivalenceBlock_.find(symbol)};
+      auto eqIter = equivalenceBlock_.find(symbol);
       if (eqIter != equivalenceBlock_.end()) {
-        SizeAndAlignment &blockInfo{eqIter->second};
-        DoEquivalenceBlockBase(symbol, blockInfo);
-        minSize = std::max(
-            minSize, std::max(offset_, symbol.offset() + blockInfo.size));
-        minAlignment = std::max(minAlignment, blockInfo.alignment);
+        DoEquivalenceBlockBase(symbol, eqIter->second);
       }
     } else {
       SymbolAndOffset &dep{iter->second};
@@ -183,10 +179,19 @@
             "'%s' cannot backward-extend COMMON block /%s/ via EQUIVALENCE with '%s'"_err_en_US,
             symbol.name(), commonBlock.name(), base.name());
       } else {
+        eqIter = equivalenceBlock_.find(base);
         base.get<ObjectEntityDetails>().set_commonBlock(commonBlock);
         base.set_offset(symbol.offset() - dep.offset);
       }
     }
+    // Get full extent of any EQUIVALENCE block into size of COMMON ( see
+    // 8.10.2.2 point 1 (2))
+    if (eqIter != equivalenceBlock_.end()) {
+      SizeAndAlignment &blockInfo{eqIter->second};
+      minSize = std::max(
+          minSize, std::max(offset_, eqIter->first->offset() + blockInfo.size));
+      minAlignment = std::max(minAlignment, blockInfo.alignment);
+    }
   }
   commonBlock.set_size(std::max(minSize, offset_));
   details.set_alignment(std::max(minAlignment, alignment_));
diff --git a/flang/test/Semantics/offsets03.f90 b/flang/test/Semantics/offsets03.f90
--- a/flang/test/Semantics/offsets03.f90
+++ b/flang/test/Semantics/offsets03.f90
@@ -37,3 +37,23 @@
   common /common1/ d3,d2,d1 !CHECK: common1 size=10 offset=0: CommonBlockDetails alignment=4:
   common /common2/ d4       !CHECK: common2 size=2 offset=0: CommonBlockDetails alignment=2:
 end
+
+! Test extension of common block size through equivalence statements.
+module me
+  integer :: i1, j1, l1(10)
+  equivalence(i1, l1)
+  common /common3/ j1, i1   ! CHECK: common3 size=44 offset=0: CommonBlockDetails alignment=4:
+
+  integer :: i2, j2, l2(10)
+  equivalence(i2, l2(2))
+  common /common4/ j2, i2   ! CHECK: common4 size=40 offset=0: CommonBlockDetails alignment=4:
+
+  integer :: i3, j3, l3(10)
+  equivalence(i3, l3)
+  common /common5/ i3, j3   ! CHECK: common5 size=40 offset=0: CommonBlockDetails alignment=4:
+
+  integer :: i4, j4, l4(10), k4(10)
+  equivalence(i4, l4)
+  equivalence(l4(10), k4)
+  common /common6/ i4, j4   ! CHECK: common6 size=76 offset=0: CommonBlockDetails alignment=4:
+end