diff --git a/icu4c/source/i18n/numfmt.cpp b/icu4c/source/i18n/numfmt.cpp
index 9d7ab667004..cf0ce6f0ed5 100644
--- a/icu4c/source/i18n/numfmt.cpp
+++ b/icu4c/source/i18n/numfmt.cpp
@@ -543,7 +543,7 @@ UnicodeString&
 NumberFormat::format(const number::impl::DecimalQuantity &number,
                      UnicodeString& appendTo,
                      FieldPosition& pos,
-                     UErrorCode &status) const { 
+                     UErrorCode &status) const {
     // DecimalFormat overrides this function, and handles DigitList based big decimals.
     // Other subclasses (ChoiceFormat) do not (yet) handle DigitLists,
     // so this default implementation falls back to formatting decimal numbers as doubles.
diff --git a/icu4c/source/i18n/unicode/decimfmt.h b/icu4c/source/i18n/unicode/decimfmt.h
index 944a9224498..863250d023f 100644
--- a/icu4c/source/i18n/unicode/decimfmt.h
+++ b/icu4c/source/i18n/unicode/decimfmt.h
@@ -1074,6 +1074,7 @@ class U_I18N_API DecimalFormat : public NumberFormat {
     UnicodeString& format(StringPiece number, UnicodeString& appendTo, FieldPositionIterator* posIter,
                           UErrorCode& status) const U_OVERRIDE;
 
+#ifndef U_HIDE_INTERNAL_API
 
     /**
      * Format a decimal number.
@@ -1111,6 +1112,8 @@ class U_I18N_API DecimalFormat : public NumberFormat {
     UnicodeString& format(const number::impl::DecimalQuantity& number, UnicodeString& appendTo,
                           FieldPosition& pos, UErrorCode& status) const U_OVERRIDE;
 
+#endif // U_HIDE_INTERNAL_API
+
     using NumberFormat::parse;
 
     /**
diff --git a/icu4c/source/i18n/unicode/numfmt.h b/icu4c/source/i18n/unicode/numfmt.h
index ada5d17dc61..57b021e5289 100644
--- a/icu4c/source/i18n/unicode/numfmt.h
+++ b/icu4c/source/i18n/unicode/numfmt.h
@@ -555,7 +555,9 @@ public:
                                   UnicodeString& appendTo,
                                   FieldPositionIterator* posIter,
                                   UErrorCode& status) const;
-public:
+
+#ifndef U_HIDE_INTERNAL_API
+
     /**
      * Format a decimal number.
      * The number is a DecimalQuantity wrapper onto a floating point decimal number.
@@ -600,7 +602,7 @@ public:
                                   FieldPosition& pos,
                                   UErrorCode& status) const;
 
-public:
+#endif // U_HIDE_INTERNAL_API
 
    /**
     * Return a long if possible (e.g. within range LONG_MAX,