diff --git a/kotlinpoet/src/main/java/com/squareup/kotlinpoet/CodeBlock.kt b/kotlinpoet/src/main/java/com/squareup/kotlinpoet/CodeBlock.kt
index 6c8e4bba4c..6a99631c12 100644
--- a/kotlinpoet/src/main/java/com/squareup/kotlinpoet/CodeBlock.kt
+++ b/kotlinpoet/src/main/java/com/squareup/kotlinpoet/CodeBlock.kt
@@ -371,6 +371,7 @@ public class CodeBlock private constructor(
       val format = DecimalFormatSymbols().apply {
         decimalSeparator = '.'
         groupingSeparator = '_'
+        minusSign = '-'
       }
 
       val precision = if (o is Float || o is Double) o.toString().split(".").last().length else 0
diff --git a/kotlinpoet/src/test/java/com/squareup/kotlinpoet/CodeBlockTest.kt b/kotlinpoet/src/test/java/com/squareup/kotlinpoet/CodeBlockTest.kt
index dc52f38e0c..be4e62dd41 100644
--- a/kotlinpoet/src/test/java/com/squareup/kotlinpoet/CodeBlockTest.kt
+++ b/kotlinpoet/src/test/java/com/squareup/kotlinpoet/CodeBlockTest.kt
@@ -17,6 +17,7 @@ package com.squareup.kotlinpoet
 
 import com.google.common.truth.Truth.assertThat
 import com.squareup.kotlinpoet.ParameterizedTypeName.Companion.parameterizedBy
+import java.util.Locale
 import kotlin.test.Test
 
 class CodeBlockTest {
@@ -627,4 +628,16 @@ class CodeBlockTest {
     assertThat(CodeBlock.of("%S", 10000.12345678901).toString()).isEqualTo("\"10000.12345678901\"")
     assertThat(CodeBlock.of("%S", 1281.toShort()).toString()).isEqualTo("\"1281\"")
   }
+
+  // https://github.com/square/kotlinpoet/issues/1657
+  @Test fun minusSignInSwedishLocale() {
+    val defaultLocale = Locale.getDefault()
+    Locale.setDefault(Locale.forLanguageTag("sv"))
+
+    val i = -42
+    val s = CodeBlock.of("val i = %L", i)
+    assertThat(s.toString()).isEqualTo("val i = -42")
+
+    Locale.setDefault(defaultLocale)
+  }
 }