diff --git a/src/common/utility/vectors.h b/src/common/utility/vectors.h
index 23452f07b..c009cb505 100644
--- a/src/common/utility/vectors.h
+++ b/src/common/utility/vectors.h
@@ -1366,12 +1366,6 @@ public:
 	}
 };
 
-// Emulates the old floatbob offset table with direct calls to trig functions.
-inline double BobSin(double fb)
-{
-	return g_sindeg(double(fb * (180.0 / 32))) * 8;
-}
-
 template<class T>
 inline TAngle<T> fabs (const TAngle<T> &deg)
 {
diff --git a/src/playsim/actorinlines.h b/src/playsim/actorinlines.h
index 3fb3676a1..56a2e6ab8 100644
--- a/src/playsim/actorinlines.h
+++ b/src/playsim/actorinlines.h
@@ -49,6 +49,12 @@ inline double sector_t::LowestFloorAt(AActor *a, sector_t **resultsec)
 	return ::LowestFloorAt(this, a->X(), a->Y(), resultsec);
 }
 
+// Emulates the old floatbob offset table with direct calls to trig functions.
+inline double BobSin(double fb)
+{
+	return g_sindeg(double(fb * (180.0 / 32))) * 8;
+}
+
 inline double AActor::GetBobOffset(double ticfrac) const
 {
 	if (!(flags2 & MF2_FLOATBOB))
diff --git a/src/playsim/mapthinkers/a_floor.cpp b/src/playsim/mapthinkers/a_floor.cpp
index ce2ba5960..3ba08087c 100644
--- a/src/playsim/mapthinkers/a_floor.cpp
+++ b/src/playsim/mapthinkers/a_floor.cpp
@@ -41,6 +41,7 @@
 #include "g_levellocals.h"
 #include "vm.h"
 #include "r_utility.h"
+#include "actorinlines.h"
 
 //==========================================================================
 //