diff --git a/interpreter/binary/decode.ml b/interpreter/binary/decode.ml
index 68a8d9c4c9..370386633b 100644
--- a/interpreter/binary/decode.ml
+++ b/interpreter/binary/decode.ml
@@ -86,7 +86,7 @@ let rec vuN n s =
 let rec vsN n s =
   require (n > 0) s (pos s) "integer representation too long";
   let b = u8 s in
-  let mask = (-1 lsl n) land 0x7f in
+  let mask = (-1 lsl (n - 1)) land 0x7f in
   require (n >= 7 || b land mask = 0 || b land mask = mask) s (pos s - 1)
     "integer too large";
   let x = Int64.of_int (b land 0x7f) in
diff --git a/test/core/binary.wast b/test/core/binary.wast
index 8cfeed46f7..2c43d0cedd 100644
--- a/test/core/binary.wast
+++ b/test/core/binary.wast
@@ -43,6 +43,231 @@
 (assert_malformed (module binary "\00asm\00\00\01\00") "unknown binary version")
 (assert_malformed (module binary "\00asm\00\00\00\01") "unknown binary version")
 
+;; Unsigned LEB128 can have non-minimal length
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\05\04\01"                          ;; Memory section with 1 entry
+  "\00\82\00"                          ;; no max, minimum 2
+)
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\05\07\01"                          ;; Memory section with 1 entry
+  "\00\82\80\80\80\00"                 ;; no max, minimum 2
+)
+
+;; Signed LEB128 can have non-minimal length
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\07\01"                          ;; Global section with 1 entry
+  "\7f\00"                             ;; i32, immutable
+  "\41\80\00"                          ;; i32.const 0
+  "\0b"                                ;; end
+)
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\07\01"                          ;; Global section with 1 entry
+  "\7f\00"                             ;; i32, immutable
+  "\41\ff\7f"                          ;; i32.const -1
+  "\0b"                                ;; end
+)
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\0a\01"                          ;; Global section with 1 entry
+  "\7f\00"                             ;; i32, immutable
+  "\41\80\80\80\80\00"                 ;; i32.const 0
+  "\0b"                                ;; end
+)
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\0a\01"                          ;; Global section with 1 entry
+  "\7f\00"                             ;; i32, immutable
+  "\41\ff\ff\ff\ff\7f"                 ;; i32.const -1
+  "\0b"                                ;; end
+)
+
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\07\01"                          ;; Global section with 1 entry
+  "\7e\00"                             ;; i64, immutable
+  "\42\80\00"                          ;; i64.const 0 with unused bits set
+  "\0b"                                ;; end
+)
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\07\01"                          ;; Global section with 1 entry
+  "\7e\00"                             ;; i64, immutable
+  "\42\ff\7f"                          ;; i64.const -1 with unused bits unset
+  "\0b"                                ;; end
+)
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\0f\01"                          ;; Global section with 1 entry
+  "\7e\00"                             ;; i64, immutable
+  "\42\80\80\80\80\80\80\80\80\80\00"  ;; i64.const 0 with unused bits set
+  "\0b"                                ;; end
+)
+(module binary
+  "\00asm" "\01\00\00\00"
+  "\06\0f\01"                          ;; Global section with 1 entry
+  "\7e\00"                             ;; i64, immutable
+  "\42\ff\ff\ff\ff\ff\ff\ff\ff\ff\7f"  ;; i64.const -1 with unused bits unset
+  "\0b"                                ;; end
+)
+
+;; Unsigned LEB128 must not be overlong
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\05\08\01"                          ;; Memory section with 1 entry
+    "\00\82\80\80\80\80\00"              ;; no max, minimum 2 with one byte too many
+  )
+  "integer representation too long"
+)
+
+;; Signed LEB128 must not be overlong
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0b\01"                          ;; Global section with 1 entry
+    "\7f\00"                             ;; i32, immutable
+    "\41\80\80\80\80\80\00"              ;; i32.const 0 with one byte too many
+    "\0b"                                ;; end
+  )
+  "integer representation too long"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0b\01"                          ;; Global section with 1 entry
+    "\7f\00"                             ;; i32, immutable
+    "\41\ff\ff\ff\ff\ff\7f"              ;; i32.const -1 with one byte too many
+    "\0b"                                ;; end
+  )
+  "integer representation too long"
+)
+
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\10\01"                          ;; Global section with 1 entry
+    "\7e\00"                             ;; i64, immutable
+    "\42\80\80\80\80\80\80\80\80\80\80\00"  ;; i64.const 0 with one byte too many
+    "\0b"                                ;; end
+  )
+  "integer representation too long"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\10\01"                          ;; Global section with 1 entry
+    "\7e\00"                             ;; i64, immutable
+    "\42\ff\ff\ff\ff\ff\ff\ff\ff\ff\ff\7f"  ;; i64.const -1 with one byte too many
+    "\0b"                                ;; end
+  )
+  "integer representation too long"
+)
+
+;; Unsigned LEB128s zero-extend
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\05\04\01"                          ;; Memory section with 1 entry
+    "\00\82\80\80\80\70"                 ;; no max, minimum 2 with unused bits set
+  )
+  "integer too large"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\05\04\01"                          ;; Memory section with 1 entry
+    "\00\82\80\80\80\40"                 ;; no max, minimum 2 with some unused bits set
+  )
+  "integer too large"
+)
+
+;; Signed LEB128s sign-extend
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0a\01"                          ;; Global section with 1 entry
+    "\7f\00"                             ;; i32, immutable
+    "\41\80\80\80\80\70"                 ;; i32.const 0 with unused bits set
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0a\01"                          ;; Global section with 1 entry
+    "\7f\00"                             ;; i32, immutable
+    "\41\ff\ff\ff\ff\0f"                 ;; i32.const -1 with unused bits unset
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0a\01"                          ;; Global section with 1 entry
+    "\7f\00"                             ;; i32, immutable
+    "\41\80\80\80\80\1f"                 ;; i32.const 0 with some unused bits set
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0a\01"                          ;; Global section with 1 entry
+    "\7f\00"                             ;; i32, immutable
+    "\41\ff\ff\ff\ff\4f"                 ;; i32.const -1 with some unused bits unset
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0f\01"                          ;; Global section with 1 entry
+    "\7e\00"                             ;; i64, immutable
+    "\42\80\80\80\80\80\80\80\80\80\7e"  ;; i64.const 0 with unused bits set
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0f\01"                          ;; Global section with 1 entry
+    "\7e\00"                             ;; i64, immutable
+    "\42\ff\ff\ff\ff\ff\ff\ff\ff\ff\01"  ;; i64.const -1 with unused bits unset
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0f\01"                          ;; Global section with 1 entry
+    "\7e\00"                             ;; i64, immutable
+    "\42\80\80\80\80\80\80\80\80\80\02"  ;; i64.const 0 with some unused bits set
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+(assert_malformed
+  (module binary
+    "\00asm" "\01\00\00\00"
+    "\06\0f\01"                          ;; Global section with 1 entry
+    "\7e\00"                             ;; i64, immutable
+    "\42\ff\ff\ff\ff\ff\ff\ff\ff\ff\41"  ;; i64.const -1 with some unused bits unset
+    "\0b"                                ;; end
+  )
+  "integer too large"
+)
+
 ;; call_indirect reserved byte equal to zero.
 (assert_malformed
   (module binary