diff --git a/src/java/org/apache/poi/sl/draw/DrawTextParagraph.java b/src/java/org/apache/poi/sl/draw/DrawTextParagraph.java
index c0c7eb21fdb..78979c97b42 100644
--- a/src/java/org/apache/poi/sl/draw/DrawTextParagraph.java
+++ b/src/java/org/apache/poi/sl/draw/DrawTextParagraph.java
@@ -383,11 +383,11 @@ protected String getRenderableText(Graphics2D graphics, TextRun tr) {
 
     String getRenderableText(TextRun tr) {
         String txt = tr.getRawText();
-        txt.replace("\t", tab2space(tr)).replace("\u000b", "\n");
+        txt = txt.replace("\t", tab2space(tr)).replace("\u000b", "\n");
 
         switch (tr.getTextCap()) {
-            case ALL: txt.toUpperCase(LocaleUtil.getUserLocale()); break;
-            case SMALL: txt.toLowerCase(LocaleUtil.getUserLocale()); break;
+            case ALL: txt = txt.toUpperCase(LocaleUtil.getUserLocale()); break;
+            case SMALL: txt = txt.toLowerCase(LocaleUtil.getUserLocale()); break;
             case NONE: break;
         }
 
diff --git a/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextRun.java b/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextRun.java
index 4c12a38d11c..47a712df80c 100644
--- a/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextRun.java
+++ b/src/ooxml/java/org/apache/poi/xslf/usermodel/XSLFTextRun.java
@@ -99,7 +99,7 @@ String getRenderableText() {
 
     String getRenderableText(String txt) {
         // TODO: finish support for tabs
-        txt.replace("\t", "  ");
+        txt = txt.replace("\t", "  ");
 
         switch (getTextCap()) {
             case ALL:
@@ -589,7 +589,9 @@ void copy(XSLFTextRun r) {
         }
 
         Double srcFontSize = r.getFontSize();
-        if (srcFontSize != getFontSize()) {
+        if (srcFontSize == null) {
+            if (getFontSize() != null) setFontSize(null);
+        } else if(!srcFontSize.equals(getFontSize())) {
             setFontSize(srcFontSize);
         }