diff --git a/src/xcms/IdOfPr.c b/src/xcms/IdOfPr.c
index e15f34fe..9f43dd38 100644
--- a/src/xcms/IdOfPr.c
+++ b/src/xcms/IdOfPr.c
@@ -61,7 +61,7 @@ XcmsFormatOfPrefix(char *prefix)
     XcmsColorSpace	**papColorSpaces;
     char		string_buf[64];
     char		*string_lowered;
-    int			len;
+    size_t		len;
 
     /*
      * While copying prefix to string_lowered, convert to lowercase
diff --git a/src/xcms/cmsColNm.c b/src/xcms/cmsColNm.c
index ab6e4e87..74729ef2 100644
--- a/src/xcms/cmsColNm.c
+++ b/src/xcms/cmsColNm.c
@@ -198,7 +198,7 @@ _XcmsParseColorString(
     XcmsColorSpace	*pColorSpace;
     char		string_buf[64];
     char		*string_lowered;
-    int			len;
+    size_t		len;
     int			res;
 
     if (ccc == NULL) {