diff --git a/layout/generic/nsBlockReflowContext.cpp b/layout/generic/nsBlockReflowContext.cpp
index f79088f43913..2839b6917d7e 100644
--- a/layout/generic/nsBlockReflowContext.cpp
+++ b/layout/generic/nsBlockReflowContext.cpp
@@ -175,7 +175,7 @@ nsBlockReflowContext::AlignBlockHorizontally(nscoord                 aWidth,
     // computations are no longer valid.
     if (aWidth != mComputedWidth) {
       if (eStyleUnit_Auto == leftUnit) {
-        aAlign.mXOffset = 0;
+        aAlign.mXOffset = mSpace.x;
         aAlign.mLeftMargin = 0;
       }
       if (eStyleUnit_Auto == rightUnit) {
diff --git a/layout/html/base/src/nsBlockReflowContext.cpp b/layout/html/base/src/nsBlockReflowContext.cpp
index f79088f43913..2839b6917d7e 100644
--- a/layout/html/base/src/nsBlockReflowContext.cpp
+++ b/layout/html/base/src/nsBlockReflowContext.cpp
@@ -175,7 +175,7 @@ nsBlockReflowContext::AlignBlockHorizontally(nscoord                 aWidth,
     // computations are no longer valid.
     if (aWidth != mComputedWidth) {
       if (eStyleUnit_Auto == leftUnit) {
-        aAlign.mXOffset = 0;
+        aAlign.mXOffset = mSpace.x;
         aAlign.mLeftMargin = 0;
       }
       if (eStyleUnit_Auto == rightUnit) {