diff --git a/README.md b/README.md
index cc9f3d69..30af5855 100644
--- a/README.md
+++ b/README.md
@@ -63,7 +63,7 @@ You can either [Install Tesseract via pre-built binary package](https://github.c
 
 Basic command line usage:
 
-    tesseract imagename outputbase [-l lang] [-psm pagesegmode] [configfiles...]
+    tesseract imagename outputbase [-l lang] [--psm pagesegmode] [configfiles...]
 
 For more information about the various command line options use `tesseract --help` or `man tesseract`. 
 
diff --git a/api/tesseractmain.cpp b/api/tesseractmain.cpp
index 74c15073..0ded1c08 100644
--- a/api/tesseractmain.cpp
+++ b/api/tesseractmain.cpp
@@ -142,7 +142,7 @@ void PrintHelpMessage(const char* program) {
       "  -l LANG[+LANG]        Specify language(s) used for OCR.\n"
       "  -c VAR=VALUE          Set value for config variables.\n"
       "                        Multiple -c arguments are allowed.\n"
-      "  -psm NUM              Specify page segmentation mode.\n"
+      "  --psm NUM             Specify page segmentation mode.\n"
       "  --oem NUM             Specify OCR Engine mode.\n"
       "NOTE: These options must occur before any configfile.\n";
 
@@ -275,6 +275,11 @@ void ParseArgs(const int argc, char** argv, const char** lang,
       noocr = true;
       *list_langs = true;
     } else if (strcmp(argv[i], "-psm") == 0 && i + 1 < argc) {
+      // The parameter -psm is deprecated and was replaced by --psm.
+      // It is still supported for compatibility reasons.
+      *pagesegmode = static_cast<tesseract::PageSegMode>(atoi(argv[i + 1]));
+      ++i;
+    } else if (strcmp(argv[i], "--psm") == 0 && i + 1 < argc) {
       *pagesegmode = static_cast<tesseract::PageSegMode>(atoi(argv[i + 1]));
       ++i;
     } else if (strcmp(argv[i], "--oem") == 0 && i + 1 < argc) {
diff --git a/doc/tesseract.1 b/doc/tesseract.1
index 95128fec..89107f03 100644
--- a/doc/tesseract.1
+++ b/doc/tesseract.1
@@ -84,7 +84,7 @@ Set value for control parameter\&. Multiple \-c arguments are allowed\&.
 The language to use\&. If none is specified, English is assumed\&. Multiple languages may be specified, separated by plus characters\&. Tesseract uses 3\-character ISO 639\-2 language codes\&. (See LANGUAGES)
 .RE
 .PP
-\fI\-psm N\fR
+\fI\--psm N\fR
 .RS 4
 Set Tesseract to only run a subset of layout analysis and assume a certain form of image\&. The options for
 \fBN\fR
@@ -139,7 +139,7 @@ pdf \- Output in pdf instead of a text file\&.
 .RE
 .RE
 .sp
-\fBNota Bene:\fR The options \fI\-l lang\fR and \fI\-psm N\fR must occur before any \fIconfigfile\fR\&.
+\fBNota Bene:\fR The options \fI\-l lang\fR and \fI\--psm N\fR must occur before any \fIconfigfile\fR\&.
 .SH "SINGLE OPTIONS"
 .PP
 \fI\-v\fR
diff --git a/doc/tesseract.1.asc b/doc/tesseract.1.asc
index 56627a93..237299fe 100644
--- a/doc/tesseract.1.asc
+++ b/doc/tesseract.1.asc
@@ -54,7 +54,7 @@ OPTIONS
 	Multiple languages may be specified, separated by plus characters.
 	Tesseract uses 3-character ISO 639-2 language codes. (See LANGUAGES)
 
-'-psm N'::
+'--psm N'::
 	Set Tesseract to only run a subset of layout analysis and assume
 	a certain form of image. The options for *N* are:
 
@@ -78,7 +78,7 @@ OPTIONS
   * hocr - Output in hOCR format instead of as a text file.
   * pdf  - Output in pdf instead of a text file.
 
-*Nota Bene:*   The options '-l lang' and '-psm N' must occur
+*Nota Bene:*   The options '-l lang' and '--psm N' must occur
 before any 'configfile'.
 
 
diff --git a/doc/tesseract.1.html b/doc/tesseract.1.html
index 90c5dae7..5e37d311 100644
--- a/doc/tesseract.1.html
+++ b/doc/tesseract.1.html
@@ -847,7 +847,7 @@ at Google since then.</p></div>
 </p>
 </dd>
 <dt class="hdlist1">
-<em>-psm N</em>
+<em>--psm N</em>
 </dt>
 <dd>
 <p>
@@ -893,7 +893,7 @@ pdf  - Output in pdf instead of a text file.
 </ul></div>
 </dd>
 </dl></div>
-<div class="paragraph"><p><strong>Nota Bene:</strong>   The options <em>-l lang</em> and <em>-psm N</em> must occur
+<div class="paragraph"><p><strong>Nota Bene:</strong>   The options <em>-l lang</em> and <em>--psm N</em> must occur
 before any <em>configfile</em>.</p></div>
 </div>
 </div>
diff --git a/doc/tesseract.1.xml b/doc/tesseract.1.xml
index 2f971caa..842c5acd 100644
--- a/doc/tesseract.1.xml
+++ b/doc/tesseract.1.xml
@@ -130,7 +130,7 @@ at Google since then.</simpara>
 </varlistentry>
 <varlistentry>
 <term>
-<emphasis>-psm N</emphasis>
+<emphasis>--psm N</emphasis>
 </term>
 <listitem>
 <simpara>
@@ -176,7 +176,7 @@ pdf  - Output in pdf instead of a text file.
 </listitem>
 </varlistentry>
 </variablelist>
-<simpara><emphasis role="strong">Nota Bene:</emphasis>   The options <emphasis>-l lang</emphasis> and <emphasis>-psm N</emphasis> must occur
+<simpara><emphasis role="strong">Nota Bene:</emphasis>   The options <emphasis>-l lang</emphasis> and <emphasis>--psm N</emphasis> must occur
 before any <emphasis>configfile</emphasis>.</simpara>
 </refsect1>
 <refsect1 id="_single_options">
diff --git a/testing/runtestset.sh b/testing/runtestset.sh
index 0c9595f9..5c2a7e7a 100755
--- a/testing/runtestset.sh
+++ b/testing/runtestset.sh
@@ -64,7 +64,7 @@ do
      srcdir="$imdir"
   fi
 #  echo "$srcdir/$page.tif"
-  $tess $srcdir/$page.tif $resdir/$page -psm 6 $config 2>&1 |grep -v "OCR Engine"
+  $tess $srcdir/$page.tif $resdir/$page --psm 6 $config 2>&1 |grep -v "OCR Engine"
   if [ -r times.txt ]
   then
     read t <times.txt