diff --git a/core/src/main/java/com/google/googlejavaformat/CommentsHelper.java b/core/src/main/java/com/google/googlejavaformat/CommentsHelper.java
index 45e507bbd..2b789612c 100644
--- a/core/src/main/java/com/google/googlejavaformat/CommentsHelper.java
+++ b/core/src/main/java/com/google/googlejavaformat/CommentsHelper.java
@@ -14,6 +14,10 @@
 
 package com.google.googlejavaformat;
 
+import com.google.googlejavaformat.Input.Tok;
+import java.util.Optional;
+import java.util.regex.Pattern;
+
 /**
  * Rewrite comments. This interface is implemented by {@link
  * com.google.googlejavaformat.java.JavaCommentsHelper JavaCommentsHelper}.
@@ -28,4 +32,19 @@ public interface CommentsHelper {
    * @return the rewritten comment
    */
   String rewrite(Input.Tok tok, int maxWidth, int column0);
+
+  static Optional<String> reformatParameterComment(Tok tok) {
+    if (!tok.isSlashStarComment()) {
+      return Optional.empty();
+    }
+    var match = PARAMETER_COMMENT.matcher(tok.getOriginalText());
+    if (!match.matches()) {
+      return Optional.empty();
+    }
+    return Optional.of(String.format("/* %s= */", match.group(1)));
+  }
+
+  Pattern PARAMETER_COMMENT =
+      Pattern.compile(
+          "/\\*\\s*(\\p{javaJavaIdentifierStart}\\p{javaJavaIdentifierPart}*)(\\Q...\\E)?\\s*=\\s*\\*/");
 }
diff --git a/core/src/main/java/com/google/googlejavaformat/Doc.java b/core/src/main/java/com/google/googlejavaformat/Doc.java
index 35acca367..d638ddb40 100644
--- a/core/src/main/java/com/google/googlejavaformat/Doc.java
+++ b/core/src/main/java/com/google/googlejavaformat/Doc.java
@@ -15,6 +15,7 @@
 package com.google.googlejavaformat;
 
 import static com.google.common.collect.Iterables.getLast;
+import static com.google.googlejavaformat.CommentsHelper.reformatParameterComment;
 import static java.lang.Math.max;
 
 import com.google.common.base.MoreObjects;
@@ -727,7 +728,7 @@ float computeWidth() {
           // Account for line comments with missing spaces, see computeFlat.
           return tok.length() + 1;
         } else {
-          return tok.length();
+          return reformatParameterComment(tok).map(String::length).orElse(tok.length());
         }
       }
       return idx != -1 ? Float.POSITIVE_INFINITY : (float) tok.length();
@@ -741,7 +742,7 @@ String computeFlat() {
       if (tok.isSlashSlashComment() && !tok.getOriginalText().startsWith("// ")) {
         return "// " + tok.getOriginalText().substring("//".length());
       }
-      return tok.getOriginalText();
+      return reformatParameterComment(tok).orElse(tok.getOriginalText());
     }
 
     @Override
diff --git a/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java b/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java
index 346324a45..d34ecc43f 100644
--- a/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java
+++ b/core/src/main/java/com/google/googlejavaformat/java/JavaCommentsHelper.java
@@ -53,11 +53,13 @@ public String rewrite(Tok tok, int maxWidth, int column0) {
     }
     if (tok.isSlashSlashComment()) {
       return indentLineComments(lines, column0);
-    } else if (javadocShaped(lines)) {
-      return indentJavadoc(lines, column0);
-    } else {
-      return preserveIndentation(lines, column0);
     }
+    return CommentsHelper.reformatParameterComment(tok)
+        .orElseGet(
+            () ->
+                javadocShaped(lines)
+                    ? indentJavadoc(lines, column0)
+                    : preserveIndentation(lines, column0));
   }
 
   // For non-javadoc-shaped block comments, shift the entire block to the correct
diff --git a/core/src/test/resources/com/google/googlejavaformat/java/testdata/B21283374.output b/core/src/test/resources/com/google/googlejavaformat/java/testdata/B21283374.output
index f98a37b2f..777303e61 100644
--- a/core/src/test/resources/com/google/googlejavaformat/java/testdata/B21283374.output
+++ b/core/src/test/resources/com/google/googlejavaformat/java/testdata/B21283374.output
@@ -14,41 +14,41 @@ class B21283374 {
 
   {
     f(
-        /*flagA=*/ Boolean.TRUE,
-        /*flagB=*/ Boolean.FALSE,
-        /*flagC=*/ Boolean.FALSE,
-        /*flagD=*/ Boolean.FALSE,
-        /*flagE=*/ Boolean.FALSE,
-        /*flagF=*/ Boolean.FALSE,
-        /*flagG=*/ Boolean.FALSE,
-        /*flagH=*/ Boolean.FALSE,
-        /*flagI=*/ Boolean.FALSE,
-        /*flagJ=*/ Boolean.FALSE,
-        /*flagK=*/ Boolean.FALSE);
+        /* flagA= */ Boolean.TRUE,
+        /* flagB= */ Boolean.FALSE,
+        /* flagC= */ Boolean.FALSE,
+        /* flagD= */ Boolean.FALSE,
+        /* flagE= */ Boolean.FALSE,
+        /* flagF= */ Boolean.FALSE,
+        /* flagG= */ Boolean.FALSE,
+        /* flagH= */ Boolean.FALSE,
+        /* flagI= */ Boolean.FALSE,
+        /* flagJ= */ Boolean.FALSE,
+        /* flagK= */ Boolean.FALSE);
 
     f(
-        /*flagA=*/ Boolean.TRUE,
-        /*flagB=*/ Boolean.FALSE,
-        /*flagC=*/ Boolean.FALSE,
-        /*flagD=*/ Boolean.FALSE,
-        /*flagE=*/ Boolean.FALSE,
-        /*flagF=*/ Boolean.FALSE,
-        /*flagG=*/ Boolean.FALSE,
-        /*flagH=*/ Boolean.FALSE,
-        /*flagI=*/ Boolean.FALSE,
-        /*flagJ=*/ Boolean.FALSE,
-        /*flagK=*/ Boolean.FALSE);
+        /* flagA= */ Boolean.TRUE,
+        /* flagB= */ Boolean.FALSE,
+        /* flagC= */ Boolean.FALSE,
+        /* flagD= */ Boolean.FALSE,
+        /* flagE= */ Boolean.FALSE,
+        /* flagF= */ Boolean.FALSE,
+        /* flagG= */ Boolean.FALSE,
+        /* flagH= */ Boolean.FALSE,
+        /* flagI= */ Boolean.FALSE,
+        /* flagJ= */ Boolean.FALSE,
+        /* flagK= */ Boolean.FALSE);
 
-    assertThat(foo.barAndBaz(/*paramName=*/ false, thingy)).isEqualTo(new Something(""));
-    assertThat(foo.barAndBaz(/*paramName=*/ false, thingy)).isEqualTo(new Something(""));
-    assertThat(foo.barAndBaz(/*paramName=*/ false, thingy)).isEqualTo(new Something(""));
+    assertThat(foo.barAndBaz(/* paramName= */ false, thingy)).isEqualTo(new Something(""));
+    assertThat(foo.barAndBaz(/* paramName= */ false, thingy)).isEqualTo(new Something(""));
+    assertThat(foo.barAndBaz(/* paramName= */ false, thingy)).isEqualTo(new Something(""));
 
-    f(/*paramName=*/ false);
+    f(/* paramName= */ false);
 
     assertThat__________________________________________________________(
-        /*paramName=*/ false, thingy);
+        /* paramName= */ false, thingy);
     assertThat__________________________________________________________(
-        /*paramName=*/ false, thingy);
+        /* paramName= */ false, thingy);
 
     f(
         arg1, /* which arg is this attached to? */
diff --git a/core/src/test/resources/com/google/googlejavaformat/java/testdata/B26694550.output b/core/src/test/resources/com/google/googlejavaformat/java/testdata/B26694550.output
index 945a40fce..aedafb779 100644
--- a/core/src/test/resources/com/google/googlejavaformat/java/testdata/B26694550.output
+++ b/core/src/test/resources/com/google/googlejavaformat/java/testdata/B26694550.output
@@ -3,15 +3,15 @@ class B26694550 {
     /* === not a param comment */
     fffffffffffffffffffffffffffffff(
         ImmutableList.copyOf(keys), /*&=*/
-        /*keepGoing=*/ false,
+        /* keepGoing= */ false,
         ggggggggggggggggggggggggggggggggggggggggggg);
     fffffffffffffffffffffffffffffff(
         ImmutableList.copyOf(keys),
-        /*keepGoing=*/ false,
+        /* keepGoing= */ false,
         ggggggggggggggggggggggggggggggggggggggggggg);
     fffffffffffffffffffffffffffffff(
         ImmutableList.copyOf(keys),
-        /*foo_bar=*/ false,
+        /* foo_bar= */ false,
         /*foo-bar=*/ false,
         ggggggggggggggggggggggggggggggggggggggggggg);
   }
diff --git a/core/src/test/resources/com/google/googlejavaformat/java/testdata/ParameterComment.input b/core/src/test/resources/com/google/googlejavaformat/java/testdata/ParameterComment.input
new file mode 100644
index 000000000..58590ac4e
--- /dev/null
+++ b/core/src/test/resources/com/google/googlejavaformat/java/testdata/ParameterComment.input
@@ -0,0 +1,26 @@
+package com.google.googlejavaformat.java.test;
+
+/** Tests for formatting of ParameterComments. */
+class Q {
+  static void f(int a) {
+    f(/*a=*/ 1);
+    f(
+        /* a= */ 1
+    );
+  }
+  static void g(int a, int b, int c, int d, int e, int f, int g, int h, int i, int j, int k) {
+    g(
+        /*a=*/ 1,
+        /*b=*/ 1,
+        /*c=*/ 1,
+        /*d=*/ 1,
+        /*e=*/ 1,
+        /*f=*/ 1,
+        /*g=*/ 1,
+        /*h=*/ 1,
+        /*i=*/ 1,
+        /*j=*/ 1,
+        /*k=*/ 1);
+    g(/*a=*/ 1, /*b=*/ 1, /*c=*/ 1, /*d=*/ 1, /*e=*/ 1, /*f=*/ 1, /*g=*/ 1, /*h=*/ 1, /*i=*/ 1);
+  }
+}
diff --git a/core/src/test/resources/com/google/googlejavaformat/java/testdata/ParameterComment.output b/core/src/test/resources/com/google/googlejavaformat/java/testdata/ParameterComment.output
new file mode 100644
index 000000000..5616ec0da
--- /dev/null
+++ b/core/src/test/resources/com/google/googlejavaformat/java/testdata/ParameterComment.output
@@ -0,0 +1,34 @@
+package com.google.googlejavaformat.java.test;
+
+/** Tests for formatting of ParameterComments. */
+class Q {
+  static void f(int a) {
+    f(/* a= */ 1);
+    f(/* a= */ 1);
+  }
+
+  static void g(int a, int b, int c, int d, int e, int f, int g, int h, int i, int j, int k) {
+    g(
+        /* a= */ 1,
+        /* b= */ 1,
+        /* c= */ 1,
+        /* d= */ 1,
+        /* e= */ 1,
+        /* f= */ 1,
+        /* g= */ 1,
+        /* h= */ 1,
+        /* i= */ 1,
+        /* j= */ 1,
+        /* k= */ 1);
+    g(
+        /* a= */ 1,
+        /* b= */ 1,
+        /* c= */ 1,
+        /* d= */ 1,
+        /* e= */ 1,
+        /* f= */ 1,
+        /* g= */ 1,
+        /* h= */ 1,
+        /* i= */ 1);
+  }
+}