diff --git a/icu4c/source/common/unames.c b/icu4c/source/common/unames.c
index 32398cdfba1..4026e434162 100644
--- a/icu4c/source/common/unames.c
+++ b/icu4c/source/common/unames.c
@@ -34,7 +34,7 @@
 /* prototypes ------------------------------------------------------------- */
 
 static const char DATA_NAME[] = "unames";
-static const char DATA_TYPE[] = "dat";
+static const char DATA_TYPE[] = "icu";
 
 #define GROUP_SHIFT 5
 #define LINES_PER_GROUP (1UL<<GROUP_SHIFT)
diff --git a/icu4c/source/common/unorm.cpp b/icu4c/source/common/unorm.cpp
index b7e3ad54d42..cf07004cf4f 100644
--- a/icu4c/source/common/unorm.cpp
+++ b/icu4c/source/common/unorm.cpp
@@ -123,7 +123,7 @@ _composePart(UChar *stackBuffer, UChar *&buffer, int32_t &bufferCapacity, int32_
 /* load unorm.dat ----------------------------------------------------------- */
 
 #define DATA_NAME "unorm"
-#define DATA_TYPE "dat"
+#define DATA_TYPE "icu"
 
 static UDataMemory *normData=NULL;
 static UErrorCode dataErrorCode=U_ZERO_ERROR;
@@ -133,7 +133,7 @@ static int32_t indexes[_NORM_INDEX_TOP]={ 0 };
 static UTrie normTrie={ 0,0,0,0,0,0,0 }, fcdTrie={ 0,0,0,0,0,0,0 }, auxTrie={ 0,0,0,0,0,0,0 };
 
 /*
- * pointers into the memory-mapped unorm.dat
+ * pointers into the memory-mapped unorm.icu
  */
 static const uint16_t *extraData=NULL,
                       *combiningTable=NULL,
diff --git a/icu4c/source/common/uprops.c b/icu4c/source/common/uprops.c
index ad4c46e6b6c..23de6053322 100644
--- a/icu4c/source/common/uprops.c
+++ b/icu4c/source/common/uprops.c
@@ -14,7 +14,7 @@
 *   created by: Markus W. Scherer
 *
 *   Implementations for mostly non-core Unicode character properties
-*   stored in uprops.dat.
+*   stored in uprops.icu.
 */
 
 #include "unicode/utypes.h"