diff --git a/app/iscissors.c b/app/iscissors.c
index a5a1bf326b..c0868dd406 100644
--- a/app/iscissors.c
+++ b/app/iscissors.c
@@ -42,6 +42,9 @@
 #ifndef M_PI
 #define M_PI    3.14159265358979323846
 #endif /* M_PI */
+#ifndef M_PI_4
+#define M_PI_4  0.78539816339744830962
+#endif /* M_PI_4 */
 
 /*  local structures  */
 
diff --git a/app/tools/gimpiscissorstool.c b/app/tools/gimpiscissorstool.c
index a5a1bf326b..c0868dd406 100644
--- a/app/tools/gimpiscissorstool.c
+++ b/app/tools/gimpiscissorstool.c
@@ -42,6 +42,9 @@
 #ifndef M_PI
 #define M_PI    3.14159265358979323846
 #endif /* M_PI */
+#ifndef M_PI_4
+#define M_PI_4  0.78539816339744830962
+#endif /* M_PI_4 */
 
 /*  local structures  */
 
diff --git a/app/tools/iscissors.c b/app/tools/iscissors.c
index a5a1bf326b..c0868dd406 100644
--- a/app/tools/iscissors.c
+++ b/app/tools/iscissors.c
@@ -42,6 +42,9 @@
 #ifndef M_PI
 #define M_PI    3.14159265358979323846
 #endif /* M_PI */
+#ifndef M_PI_4
+#define M_PI_4  0.78539816339744830962
+#endif /* M_PI_4 */
 
 /*  local structures  */