diff --git a/icu4c/source/common/static_unicode_sets.cpp b/icu4c/source/common/static_unicode_sets.cpp
index 9e731f5781e..5d598a0e33b 100644
--- a/icu4c/source/common/static_unicode_sets.cpp
+++ b/icu4c/source/common/static_unicode_sets.cpp
@@ -27,6 +27,7 @@ UnicodeSet* gUnicodeSets[COUNT] = {};
 
 // Save the empty instance in static memory to have well-defined behavior if a
 // regular UnicodeSet cannot be allocated.
+alignas(UnicodeSet)
 char gEmptyUnicodeSet[sizeof(UnicodeSet)];
 
 // Whether the gEmptyUnicodeSet is initialized and ready to use.
diff --git a/icu4c/source/i18n/number_decimfmtprops.cpp b/icu4c/source/i18n/number_decimfmtprops.cpp
index 6754fe19eca..12fe7060e2d 100644
--- a/icu4c/source/i18n/number_decimfmtprops.cpp
+++ b/icu4c/source/i18n/number_decimfmtprops.cpp
@@ -15,6 +15,7 @@ using namespace icu::number::impl;
 
 namespace {
 
+alignas(DecimalFormatProperties)
 char kRawDefaultProperties[sizeof(DecimalFormatProperties)];
 
 icu::UInitOnce gDefaultPropertiesInitOnce = U_INITONCE_INITIALIZER;