diff --git a/icu4c/source/Doxyfile.in b/icu4c/source/Doxyfile.in
index 5de5b832fe3..8c6c5deb220 100644
--- a/icu4c/source/Doxyfile.in
+++ b/icu4c/source/Doxyfile.in
@@ -194,7 +194,7 @@ EXPAND_ONLY_PREDEF     = YES
 SEARCH_INCLUDES        = YES
 INCLUDE_PATH           = 
 INCLUDE_FILE_PATTERNS  = 
-PREDEFINED             = U_EXPORT2= U_STABLE= U_DRAFT= U_INTERNAL= U_SYSTEM= U_DEPRECATED= U_OBSOLETE= U_CALLCONV= U_CDECL_BEGIN= U_CDECL_END=  U_NO_THROW=\  "U_NAMESPACE_BEGIN=namespace icu{" "U_NAMESPACE_END=}" U_SHOW_CPLUSPLUS_API=1 U_DEFINE_LOCAL_OPEN_POINTER()= U_IN_DOXYGEN=1 U_OVERRIDE= U_FINAL=final UCONFIG_ENABLE_PLUGINS=1 U_CHAR16_IS_TYPEDEF=0 U_CPLUSPLUS_VERSION=11 U_WCHAR_IS_UTF16 U_NOEXCEPT=
+PREDEFINED             = U_EXPORT2= U_STABLE= U_DRAFT= U_INTERNAL= U_SYSTEM= U_DEPRECATED= U_OBSOLETE= U_CALLCONV_FPTR= U_CALLCONV= U_CDECL_BEGIN= U_CDECL_END=  U_NO_THROW=\  "U_NAMESPACE_BEGIN=namespace icu{" "U_NAMESPACE_END=}" U_SHOW_CPLUSPLUS_API=1 U_DEFINE_LOCAL_OPEN_POINTER()= U_IN_DOXYGEN=1 U_OVERRIDE= U_FINAL=final UCONFIG_ENABLE_PLUGINS=1 U_CHAR16_IS_TYPEDEF=0 U_CPLUSPLUS_VERSION=11 U_WCHAR_IS_UTF16 U_NOEXCEPT=
 EXPAND_AS_DEFINED      = 
 SKIP_FUNCTION_MACROS   = YES
 #---------------------------------------------------------------------------
diff --git a/icu4c/source/common/unicode/platform.h b/icu4c/source/common/unicode/platform.h
index 4bb4ecb4122..4d2deb2d361 100644
--- a/icu4c/source/common/unicode/platform.h
+++ b/icu4c/source/common/unicode/platform.h
@@ -830,6 +830,16 @@ namespace std {
 #    define U_CALLCONV U_EXPORT2
 #endif
 
+/**
+ * \def U_CALLCONV_FPTR
+ * Similar to U_CALLCONV, but only used on function pointers.
+ * @internal
+ */
+#if U_PLATFORM == U_PF_OS390 && defined(__cplusplus)
+#    define U_CALLCONV_FPTR U_CALLCONV
+#else
+#    define U_CALLCONV_FPTR
+#endif
 /* @} */
 
 #endif
diff --git a/icu4c/source/common/unicode/uclean.h b/icu4c/source/common/unicode/uclean.h
index 5beb1f7c37a..5b0486d3950 100644
--- a/icu4c/source/common/unicode/uclean.h
+++ b/icu4c/source/common/unicode/uclean.h
@@ -149,7 +149,7 @@ typedef void  U_CALLCONV UMemFreeFn (const void *context, void *mem);
  *  @system
  */  
 U_STABLE void U_EXPORT2 
-u_setMemoryFunctions(const void *context, UMemAllocFn * U_CALLCONV a, UMemReallocFn * U_CALLCONV r, UMemFreeFn * U_CALLCONV f, 
+u_setMemoryFunctions(const void *context, UMemAllocFn * U_CALLCONV_FPTR a, UMemReallocFn * U_CALLCONV_FPTR r, UMemFreeFn * U_CALLCONV_FPTR f, 
                     UErrorCode *status);
 
 U_CDECL_END