1 files changed, 4 insertions, 1 deletions
diff --git a/math.c b/math.c
index 9ac898f0ba..c3fe7dbd09 100644
--- a/math.c
+++ b/math.c
@@ -750,7 +750,7 @@ ruby_tgamma(const double d)
 #define tgamma(d) ruby_tgamma(d)
 #endif
 
-#if defined LGAMMA_R_M0_FIX
+#if defined LGAMMA_R_PM0_FIX
 static inline double
 ruby_lgamma_r(const double d, int *sign)
 {
@@ -759,6 +759,9 @@ ruby_lgamma_r(const double d, int *sign)
 	if (d == 0.0 && signbit(d)) {
 	    *sign = -1;
 	    return INFINITY;
+	} else if (d == 0.0 && !signbit(d)) {
+	    *sign = 1;
+	    return INFINITY;
 	}
     }
     return g;