diff --git a/math.c b/math.c
index a09d605..849d822 100644
--- a/math.c
+++ b/math.c
@@ -73,23 +73,23 @@ math_atan2(VALUE obj, VALUE y, VALUE x)
     dx = RFLOAT_VALUE(x);
     dy = RFLOAT_VALUE(y);
     if (dx == 0.0 && dy == 0.0) {
-	if (!signbit(dx))
-	    return DBL2NUM(dy);
+        if (!signbit(dx))
+            return DBL2NUM(dy);
         if (!signbit(dy))
-	    return DBL2NUM(M_PI);
-	return DBL2NUM(-M_PI);
+            return DBL2NUM(M_PI);
+        return DBL2NUM(-M_PI);
     }
 #ifndef ATAN2_INF_C99
     if (isinf(dx) && isinf(dy)) {
-	/* optimization for FLONUM */
-	if (dx < 0.0) {
-	    const double dz = (3.0 * M_PI / 4.0);
-	    return (dy < 0.0) ? DBL2NUM(-dz) : DBL2NUM(dz);
-	}
-	else {
-	    const double dz = (M_PI / 4.0);
-	    return (dy < 0.0) ? DBL2NUM(-dz) : DBL2NUM(dz);
-	}
+        /* optimization for FLONUM */
+        if (dx < 0.0) {
+            const double dz = (3.0 * M_PI / 4.0);
+            return (dy < 0.0) ? DBL2NUM(-dz) : DBL2NUM(dz);
+        }
+        else {
+            const double dz = (M_PI / 4.0);
+            return (dy < 0.0) ? DBL2NUM(-dz) : DBL2NUM(dz);
+        }
     }
 #endif
     return DBL2NUM(atan2(dy, dx));
@@ -464,7 +464,7 @@ math_log(int argc, const VALUE *argv, VALUE obj)
     rb_scan_args(argc, argv, "11", &x, &base);
     d = math_log1(x);
     if (argc == 2) {
-	d /= math_log1(base);
+        d /= math_log1(base);
     }
     return DBL2NUM(d);
 }
@@ -481,7 +481,7 @@ math_log1(VALUE x)
         x = rb_big_rshift(x, SIZET2NUM(numbits));
     }
     else {
-	numbits = 0;
+        numbits = 0;
     }
 
     Need_Float(x);
@@ -537,7 +537,7 @@ math_log2(VALUE obj, VALUE x)
         x = rb_big_rshift(x, SIZET2NUM(numbits));
     }
     else {
-	numbits = 0;
+        numbits = 0;
     }
 
     Need_Float(x);
@@ -579,7 +579,7 @@ math_log10(VALUE obj, VALUE x)
         x = rb_big_rshift(x, SIZET2NUM(numbits));
     }
     else {
-	numbits = 0;
+        numbits = 0;
     }
 
     Need_Float(x);
@@ -854,11 +854,11 @@ math_gamma(VALUE obj, VALUE x)
     if (isinf(d0) && signbit(d0)) domain_error("gamma");
     fracpart = modf(d0, &intpart);
     if (fracpart == 0.0) {
-	if (intpart < 0) domain_error("gamma");
-	if (0 < intpart &&
-	    intpart - 1 < (double)numberof(fact_table)) {
-	    return DBL2NUM(fact_table[(int)intpart - 1]);
-	}
+        if (intpart < 0) domain_error("gamma");
+        if (0 < intpart &&
+            intpart - 1 < (double)numberof(fact_table)) {
+            return DBL2NUM(fact_table[(int)intpart - 1]);
+        }
     }
     d = tgamma(d0);
     return DBL2NUM(d);
@@ -888,8 +888,8 @@ math_lgamma(VALUE obj, VALUE x)
     d0 = RFLOAT_VALUE(x);
     /* check for domain error */
     if (isinf(d0)) {
-	if (signbit(d0)) domain_error("lgamma");
-	return rb_assoc_new(DBL2NUM(INFINITY), INT2FIX(1));
+        if (signbit(d0)) domain_error("lgamma");
+        return rb_assoc_new(DBL2NUM(INFINITY), INT2FIX(1));
     }
     d = lgamma_r(d0, &sign);
     v = DBL2NUM(d);