diff --git a/js/src/asmjs/AsmJSValidate.cpp b/js/src/asmjs/AsmJSValidate.cpp
index 7ace79ac5527..3134ac6320ed 100644
--- a/js/src/asmjs/AsmJSValidate.cpp
+++ b/js/src/asmjs/AsmJSValidate.cpp
@@ -4424,7 +4424,7 @@ CheckMathClz32(FunctionCompiler &f, ParseNode *call, MDefinition **def, Type *ty
         return f.failf(arg, "%s is not a subtype of intish", argType.toChars());
 
     *def = f.unary<MClz>(argDef);
-    *type = Type::Signed;
+    *type = Type::Fixnum;
     return true;
 }
 
diff --git a/js/src/jit-test/tests/asm.js/testMathLib.js b/js/src/jit-test/tests/asm.js/testMathLib.js
index af566fbb5691..5c2eb9db462e 100644
--- a/js/src/jit-test/tests/asm.js/testMathLib.js
+++ b/js/src/jit-test/tests/asm.js/testMathLib.js
@@ -64,11 +64,13 @@ for (n of [-Math.pow(2,31)-1, -Math.pow(2,31), -Math.pow(2,31)+1, -1, 0, 1, Math
 var f = asmLink(asmCompile('glob', USE_ASM + 'var clz32=glob.Math.clz32; function f(i) { i=i|0; return clz32(i)|0 } return f'), this);
 for (n of [0, 1, 2, 15, 16, Math.pow(2,31)-1, Math.pow(2,31), Math.pow(2,31)+1, Math.pow(2,32)-1, Math.pow(2,32), Math.pow(2,32)+1])
     assertEq(f(n), Math.clz32(n|0));
+assertEq(asmLink(asmCompile('glob', USE_ASM + 'var clz32=glob.Math.clz32; function f(i, j) { i=i|0;j=j|0; return (clz32(i) < (j|0))|0 } return f'), this)(0x1, 30), 0);
+assertEq(asmLink(asmCompile('glob', USE_ASM + 'var clz32=glob.Math.clz32; function f(i, j) { i=i|0;j=j|0; return (clz32(i) < (j>>>0))|0 } return f'), this)(0x1, 30), 0);
 
 var doubleNumbers = [NaN, Infinity, -Infinity, -10000, -3.4, -0, 0, 3.4, 10000];
 var floatNumbers = [];
 for (var x of doubleNumbers) floatNumbers.push(Math.fround(x));
-var intNumbers = [-Math.pow(2,31), -10000, -3, -1, 0, 3, 10000, Math.pow(2,31)];
+var intNumbers = [-Math.pow(2,31), -10000, -3, -1, 0, 3, 10000, Math.pow(2,31), Math.pow(2,31)+1];
 
 function testBinary(f, g, numbers) {
     for (n of numbers)